Design & Build

Data Center Solution-Design Guide: Connecting VCS Fabric to Spanning Tree Protocol (STP) Networks

by ‎05-28-2014 08:48 AM - edited ‎08-06-2014 08:50 AM (8,448 Views)

 

SYNOPSIS:Provides design guidance for how to use Brocade VCS Fabric with existing networks that are configured for Spanning Tree Protocol (STP). Starting with Network Operating System (NOS) 4.0, Brocade VDX Swithes in VCS Fabric mode support STP, RSTP, PVST+, MSTP and RPVST+ versions of STP.

 

 

 

Preface

Overview

This document is a design guide for using VCS Fabrics with existing Spanning Tree Protocol (STP) including existing Cisco’s Catalyst Switches. It includes example commands and test results for various STP protocols including STP, RSTP, PVST+, MSTP, RPVST+.

 

Network OS (NOS) 4.0.x, Brocade VDX Switches support multiple methods to integrate with existing STP (Spanning Tree Protocol) networks:

 

  • In Standalone mode, Brocade VDX Switches support STP, and therefore, VDX Switches in Standalone mode actively participates in Root Bridge election and Designated Port election by sending STP BPDU (Bridge Protocol Data Units) frames and processing received STP BPDU frames. For how to connect VDX Switches in Standalone mode to existing STP networks, please use the following references.

 

References

 

  • In VCS Fabric mode, by default Brocade VDX Switches do not enable STP, but pass through STP BPDU frames. Therefore, VDX Switches with NOS 4.0.x in VCS Fabric mode do not send STP BPDU frames and do not process received STP BPDU frames. They only pass STP BPDU frames across the VCS Fabric to ports in the same VLAN. For how to connect VDX Switches in Fabric mode that do not enable STP to existing STP networks, please use the following reference.

 

References

 

  • Starting with NOS 4.0.0, VDX switches in VCS Fabric mode support STP. VDX switches can actively participate in Root Bridge election and Designated Port election by sending STP BPDU (Bridge Protocol Data Units) frames and processing received STP BPDU frames. This preserves the benefits of a VCS Fabric when connected to switches (other vendor and Brocade) configured with legacy STP.

 

This design guide discusses how to connect Brocade VDX Switches with NOS 4.0.x in VCS Fabric mode to a network of existing Cisco Catalyst switches using STP.

 

The following Brocade and Cisco platforms are used in this deployment guide.

  • Brocade VDX switches
  • Cisco Catalyst 6500 Switch and 3750 Switch

 

Audience

This document is intended for network design and operation staff that want to add a Brocade VCS Fabric to an existing data center network with Cisco Switches running STP.

 

Objectives

This design guide provides guidance, recommendations and example configuration commands to connect Brocade VDX Switchs in VCS Fabric mode to an existing data center network with Cisco Switches running various types of Spanning Tree Protocol including STP, RSTP, PVST+, MSTP,. RPVST+.

 

Related Documents

The following documents are valuable resources for the designer. In addition, any Brocade release notes that have been published for Brocade VDX Switches should be reviewed.

 

References

 

About Brocade

Brocade®(NASDAQ: BRCD)networking solutions help the world’s leading organizationstransition smoothly to a world where applications and information reside anywhere.This vision is designed to deliver key business benefits such as unmatched simplicity, non-stop networking, application optimization, and investment protection.

 

Innovative Ethernet and storage networking solutions for data center, campus, and service provider networks help reduce complexity and cost while enabling virtualization and cloud computing to increase business agility.

 

To help ensure a complete solution, Brocade partners with world-class IT companies and provides comprehensive education, support, and professional services offerings. (www.brocade.com)

 

Key Contributors

The content in this guide was developed by the following key contributors.

  • Lead Architect:          Chris Yoon, Strategic Solutions Lab
  • Technical Author:     Brook Reams, Strategic Solutions Lab

 

Document History

Date                    Version        Description

2014-05-15       1.0                  Initial Release

 

Spanning Tree Protocol in VCS Fabric

 

Starting with VCS Fabric NOS 4.0.x, VDX switches support STP. The VCS Fabric switch ports that have STP enabled actively participate in Root Bridge election and Designated Port election by sending STP BPDU (Bridge Protocol Data Unit) frames and processing received STP BPDU frames. This capability is called DiST (Distributed Spanning Tree Protocol). With DiST a VCS Fabric appears as a single bridge to external non-VCS Fabric switches. DiST is enabled on VCS edge ports connecting to a different VCS Fabric or to standalone L2 Switches from Brocade and other vendors.

 

There are two operational modes for a Brocade VCS Fabric, and STP configuration is different depending on the operational mode selected.

 

  • Logical Chassis Cluster mode: This mode requires NOS 4.0.0 or higher. Both the data and configuration paths are distributed and the entire cluster is configured from the principal node. After configuring global STP setting on the principal node, STP can be enabled on edge ports.

 

  • Fabric Cluster mode: In this mode, the data path for nodes is distributed, but the configuration path is not distributed. Each node has its own independent configuration database. After a STP configuration is set on all the switches in the fabric, STP can be enabled on edge ports. It is important to note that in Fabric Cluster mode, the STP configuration must be the same on all the member nodes of a VCS Fabric. Mismatched configuration of STP on the switches in a VCS Fabric is not supported. For example, the VCS Fabric will not form if one of the switches in a VCS Fabric is configured for RSTP and another the others are configured for STP or MSTP.

STP Port Cost in VCS Fabric

 

Default STP Port Cost

In VCS Fabric, long mode STP port cost values are used for the default STP port cost. For example, the default STP cost for a 10Gbps interface is 2,000 as shown in the table below.

 

STP Port Cost Value

Bandwidth

Short Mode STP

port cost value

Long Mode STP

port cost value

10 Mbps

100

2,000,000

100 Mbps

19

200,000

1 Gbps

4

20,000

N X 1 Gbps

3

10,000

10 Gbps

2

2,000

100 Gbps

N/A

200

1 Tbps

N/A

20

10 Tbps

N/A

2

Port Channel’s STP Port Cost

 

In VCS Fabric, there are two options for setting STP port cost for a port-channel, Custom and Standard. The default is standard.

  • Custom: The STP port cost changes according to the port-channel’s bandwidth.
  • Standard: The STP port cost does not change according to the port-channel’s bandwidth.

 

To specify port cost for a port-channel, perform the following steps from privileged EXEC mode:

  1.     Enter the configure terminal command to access global configuration mode.
  2.     Enter the appropriate protocol command to enable STP, RSTP, MSTP, PVST+, or R-PVST+.
                switch(config)# protocol spanning-tree stp
  3.     Specify the port-channel path cost.
                switch(conf-stp)# port-channel path-cost custom

 

The following shows that when port-channel 1 and port-channel 2 are configured with two 10Gbps ports using the default value for STP port cost, the STP port cost is 2,000 for each port-channel.

 

--------------

VCS1# show spanning-tree brief

 Spanning-tree Mode: Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0017.0fec.f800

                   Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 32768

                   Address 01e0.5200.0152

                   Root Port Po 1

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role  Sts     Cost       Prio  Link-type    Edge

 ------------------------------------------------------------------------

 Po 1          RTPT  LRN  2000       128   P2P            No 

 Po 2          ALT     BLK   2000       128   P2P            No  

---------------

 

 

The following shows that when port-channel 1 and port-channel 2 are configured with two 10Gbps each, and the STP port cost uses a Custom configuration, the STP port cost is 1,000 which is the port cost for a 20 Gbps link.

 

--------------

VCS1# show spanning-tree brief

 

 Spanning-tree Mode: Spanning Tree Protocol

 

      Root ID      Priority 0

                         Address 0017.0fec.f800

                         Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 32768

                           Address 01e0.5200.0152

                           Root Port Po 1

                           Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role  Sts  Cost       Prio  Link-type        Edge

 ---------------------------------------------------------------------

 Po 1          RTPT  FWD  1000       128   P2P               No 

 Po 2          ALT      BLK  1000        128   P2P               No 

------------------

 

STP Deployment Scenarios

 

In current VCS Fabric deployment scenarios, it’s possible to have loop in layer 2 data plane if multiple VCS Fabrics are connected together. DiST allows any flavors of Spanning Tree protocol running on the VCS Fabric, and its purpose is to create a loop-free L2 network between interconnecting VCS Fabrics or between VCS and other vendor switches. The STP support on VCS Fabric not only provides loop-free inter-VCS datacenter but also provides the customers a deployment plan to integrate Brocade VCS cloud network to existing STP network. 

 

In summary, the use cases for DiST are:

  1. To support VCS Fabric to VCS Fabric connectivity with automatic loop detection and prevention.
  2. To assist deployment plans for customers, for integrating Brocade VCS Fabric with existing STP networks or to replace STP enabled switches in a network.
  3. To eliminate the need for VCS Standalone when using STP with VDX switches. 

 

VCS Fabric with NOS 4.0.x supports any of the following types of STP:

  • IEEE 802.1D STP
  • IEEE 802.1w RSTP
  • IEEE 802.1s MSTP
  • PVST+
  • RPVST+

 

DiST Topology Support

Four different topologies supported by DiST as shown below:

 

  1. VCS Fabric with multiple VDXs (that is, multi nodes’ VCS Fabric) interconnected with L2 switches: Integrate Brocade VCS cloud network to existing STP network or replacing the legacy STP enabled switches in network.

DiSTinMulti-switchVCSFabric .jpg

   DiST in Multi-switch VCS Fabric

 

  1. VCS Fabric with single VDX (that is, single node VCS Fabric) interconnected with L2 switches: Eliminate the deployment need for standalone mode to be able to run STP, and customer can deploy VCS Fabric with single VDX. 

 DiSTinSingleSwitchVCSFabric.jpg

   DiST in Single Switch VCS Fabric

 

  1. Interconnected VCS Fabrics: Support VCS Fabric to VCS Fabric connectivity, and automatic loop detection and prevention.

 DiSTinMulti-VCSFabrics.jpg

   DiST in Multi-VCS Fabrics

 

  1. Mixed single node and multi-node VCS Fabrics with other vendor switches interconnected with lags/vLAGS:

 DiSTinHeterogenousFabricsandL2Switches .png

   DiST in Heterogenous Fabrics with L2 Switches

 

VCS Fabric STP Interoperability with Cisco Switches

The following sections review how to configure various types of STP on Brocade VCS Fabric for interoperability with Cisco Catalyst switches.

 

802.1D STP

 

Overview

IEEE 802.1D STP assumes one Spanning Tree instance for the entire bridged network, regardless of the number of VLANs. This implementation reduces CPU load since only one Spanning Tree instance is maintained for the entire network. However, this implementation can be used when only one Layer 2 topology is needed in the network. Since there is one Spanning Tree instance for the entire network, it does not have the ability to load balance Layer 2 traffic by forwarding some VLANs on one 802.1Q (dot1q) trunk and other VLANs on another 802.1Q (dot1q) trunk.

 

Configurations

The following is an IEEE 802.1D STP configuration with sample output from the VCS Fabric show command:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree stp

 port-channel path-cost custom

!

VCS1# show spanning-tree br

 

 Spanning-tree Mode: Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0017.0fec.f800

                   Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 32768

                   Address 01e0.5200.0152

                   Root Port Po 1

 

!--- This was newly added for DIST to identify the root port in a cluster.

 

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role    Sts      Cost   Prio   Link-type  Edge

 -----------------------------------------------------------------------

 Po 1          RTPT    FWD  1000    128   P2P           No 

 Po 2          ALT       BLK    1000    128   P2P           No 

-------------------

 

802.1D STP Interoperability

Natively, Cisco switches run a separate STP instance for each configured and active VLAN which is called Per-VLAN Spanning Tree (PVST). Switches not have configuration to enable 802.1D STP directly. However, using Multiple Spanning Tree Protocol (MSTP), VLANs can be grouped into a single instance on Cisco switches. MSTP uses BPDU version 3 which is backward compatible with the 802.1D STP which uses BPDU version 0.

 

By default, all VLANs in a Cisco Catalyst switch in MSTP mode are grouped into IST0, which is called the Internal Spanning Tree (IST) and MST instance 0. 802.1D STP is interoperable with Cisco Catalyst switches using MST0.

 

The configuration below shows how MSTP is configured on Cisco Catalyst switches, Once MSTP is enabled, by default, all the VLANs are grouped into IST0 and MST instance 0.

 

-------------------

Cat6500-A#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree mst 0 priority 0

 

Cat6500-A#sh spanning-tree mst

 

##### MST0    vlans mapped:   1-4094

Bridge        address 0017.0fec.f800  priority      0     (0 sysid 0)

Root          this switch for the CIST

Operational   hello time 2 , forward delay 15, max age 20, txholdcount 6

Configured    hello time 2 , forward delay 15, max age 20, max hops    20

 

Interface        Role  Sts     Cost      Prio.Nbr    Type

---------------- ---- --- --------- -------- --------------------------------

Gi1/14           Desg FWD 20000    128.14       P2p

Te2/3             Desg FWD 2000      128.131     P2p

Po1                Desg FWD 1000      128.1665   P2p

-------------------

 

802.1w RSTP

 

Overview

IEEE 802.1w RSTP is an evolution of the 802.1D standard. It provides rapid convergence following the failure of a switch, a switch port, or a LAN. It provides rapid convergence of edge ports, new root ports, and ports connected through point-to-point links.

 

The 802.1D STP terminology remains primarily the same. Most parameters have been left unchanged, so network administrators familiar with 802.1D STP can easily configure RSTP. 802.1w RSTP can also revert back to 802.1D STP in order to interoperate with legacy bridges on a per-port basis. This drops the benefits it introduces.

 

The states for a  Layer 2 interface running RSTP are:

  1. Learning: The interface prepares to participate in frame forwarding.
  2. Forwarding: The interface forwards frames.
  3. Discarding: The interface discards frames. Note that the 802.1D disabled, blocking, and listening states are merged into a single RSTP state, discarding. Ports in the discarding state do not take part in the active topology and do not learn MAC addresses.

 

Configurations

The following are IEEE 802.1w RSTP configurations and sample output from the show command on a VCS Fabric:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree rstp

 port-channel path-cost custom

!

 

VCS1# show spanning-tree br

 

 Spanning-tree Mode: Rapid Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0017.0fec.f800

                          Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 32768

                           Address 01e0.5200.0152

                           Root Port Po 1

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                           Migrate Time 3 sec

 

 Interface     Role  Sts  Cost       Prio  Link-type     Edge

 -----------------------------------------------------------------------

 Po 1          RTPT  FWD  1000    128   P2P             No 

 Po 2          ALT      DSC  1000    128   P2P             No 

 

-------------------

 

801.w RSTP Interoperability

Natively, Cisco Catalyst switches run a separate STP instance for each configured and active VLAN which is called Rapid Per-VLAN Spanning Tree (RPVST). Cisco Catalyst switches do not provide a configuration option to enable 802.1w RSTP in a direct manner. However, with MSTP, VLANs can be grouped into a single instance on Cisco Catalyst switches, and MSTP is fully compatible with RSTP, in that MSTP BPDUs can be interpreted by an RSTP switch as a RSTP BPDUs.

 

By default, all VLANs in a Cisco Catalyst switch in MSTP mode are grouped into IST0, which is called an Internal Spanning Tree (IST) and MST instance 0. 802.1w STP is interoperable with Cisco Switches using MST0.  The following shows how MSTP is configured on Cisco switches, and once MSTP is enabled, by default, all the VLANs are grouped into IST0 and MST instance 0 as shown below:

 

-------------------

Cat6500-A#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree mst 0 priority 0

 

Cat6500-A#sh spanning-tree mst

 

##### MST0    vlans mapped:   1-4094

Bridge        address 0017.0fec.f800  priority      0     (0 sysid 0)

Root            this switch for the CIST

Operational   hello time 2 , forward delay 15, max age 20, txholdcount 6

Configured    hello time 2 , forward delay 15, max age 20, max hops    20

 

Interface        Role Sts     Cost      Prio.Nbr     Type

---------------- ---- --- --------- -------- --------------------------------

Gi1/14           Desg FWD  20000   128.14       P2p

Te2/3             Desg FWD 2000      128.131    P2p

Po1                Desg FWD 1000      128.1665  P2p

-------------------

 

PVST+

 

Overview

Per-VLAN Spanning Tree+ (PVST+) maintains a Spanning Tree instance for each VLAN configured in the network. It uses 802.1Q (dot1q) trucking and allows a VLAN trunk to be forwarding for some VLANs and blocking for other VLANs. Since PVST treats each VLAN as a separate network, it has the ability to load balance Layer 2 traffic by forwarding some VLANs on one trunk and other VLANs on another trunk without causing a forwarding loop.

 

PVST+ is not a scalable model when there are many VLANs in the network as it consumes a lot of CPU cycles. By default, Cisco Catalyst switches enable PVST+ instead of 802.1D STP.

 

Configurations

The following is a PVST+ configuration with sample output from the show command in a VCS Fabric:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree pvst

 port-channel path-cost custom

!

 

VCS1# show spanning-tree vlan 501 brief

VLAN 501

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0017.0fec.f9f5

                   Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 33269

                   Address 01e0.5200.0152

                   Root Port Po 1

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role  Sts      Cost       Prio  Link-type  Edge

 -----------------------------------------------------------------------

 Po 1          RTPT  FWD  1000       128   P2P           No 

 Po 2          ALT     BLK    1000       128   P2P           No 

 

VCS1# show spanning-tree vlan 502 brief

VLAN 502

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0019.0762.99f6

                   Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 33270

                   Address 01e0.5200.0152

                   Root Port Po 2

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role  Sts     Cost       Prio  Link-type   Edge

 ------------------------------------------------------------------------

 Po 1          ALT      BLK  1000       128   P2P            No 

 Po 2          RTPT  LRN  1000       128   P2P            No 

 

-------------------

 

PVST+ Interoperability

Brocade VDX Switches support PVST+, but PVST is proprietary to Cisco and is not supported. To interoperate with Cisco Switches in PVST+ mode, the spanning-tree bpdu-mac command must be configured for the interfaces in the VCS Fabric switches that connect to the Cisco switches.

 

-------------------

switch(config)#interface tengigabitethernet x/x

switch(conf-if-te-0/12)#spanning-tree bpdu-mac 0100.0ccc.cccd

-------------------

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree pvst

 port-channel path-cost custom

!

 

VCS1# show spanning-tree vlan 501 br

VLAN 501

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0017.0fec.f9f5

                   Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 33269

                   Address 01e0.5200.0152

                   Root Port Po 1

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role    Sts    Cost       Prio   Link-type   Edge

 ---------------------------------------------------------------------

 Po 1            RTPT  FWD  1000      128   P2P           No 

 Po 2            ALT     BLK   1000       128   P2P           No 

 

 

Cat6500-A#sh run | in spanning-tree

spanning-tree mode pvst

spanning-tree vlan 501 priority 0

 

Cat6500-A#sh spanning-tree vlan 501

 

VLAN0501

  Spanning tree enabled protocol ieee

  Root ID    Priority    0

             Address     0017.0fec.f9f5

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0   

             Address     0017.0fec.f9f5

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time 300

 

Interface           Role    Sts       Cost   Prio.Nbr    Type

------------------- -------- --------- --------  -------------------------------

Gi1/14              Desg   FWD    4        128.14        P2p

Te2/3               Desg   FWD     2        128.131     P2p

Po1                  Desg   FWD    1        128.1665    P2p

-------------------

 

 

MSTP

 

Overview

The IEEE 802.1s MSTP creates multiple loop-free active spanning tree topologies on a single physical topology. MSTP allows multiple VLANs to be mapped to the same spanning tree instance (forwarding path) reducing the number of spanning tree instances needed to support a large number of VLANs.

 

Each MSTP instance has a Spanning Tree topology independent of other Spanning Tree instances. With MSTP you can have multiple forwarding paths for data traffic. A failure in one instance does not affect other instances. With MSTP, you are able to more effectively utilize the physical resources present in the network and achieve better load balancing of VLAN traffic.

 

The following diagram shows a common design. Switch A with 1,000 VLANs is redundantly connected to two distribution Switches, D1 and D2. In this topology, when users are connected to access Switch A, the network administrator is able to achieve load balancing on the access switch uplinks by mapping half of the 1,000 VLANs to a different MSTP instance. In MSTP mode, RSTP is automatically enabled to provide rapid convergence.

 

LoadBalancingUsingMSTPInstances.jpg

   Load Balancing Using MSTP Instances

 

Configurations

Multiple switches must be configured with the same MSTP configuration, called and MSTP region, to participate in multiple spanning tree instances. Brocade supports 32 MSTP instances and one MSTP region. MSTP introduces a hierarchical way of managing switch domains using regions. Switches that share common MSTP configuration attributes belong to a region. The MSTP configuration determines the MSTP region where each switch resides. The common MSTP configuration attributes are:

  • Alphanumeric configuration name (32 bytes)
  • Configuration revision number (2 bytes)
  • Configuration identifier format selector
  • Message digest key

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree mstp

 port-channel path-cost custom

 instance 1 vlan 1,501

 instance 2 vlan 502

 region VCS_Fabric

 revision 10

!

VCS1# show spanning-tree mst      

 

 Spanning-tree Mode: Multiple Spanning Tree Protocol

 

 CIST Root Id: 0000.0017.0fec.f800

 CIST Bridge Id: 8000.01e0.5200.0152

 CIST Reg Root Id: 0000.0017.0fec.f800

 

 CIST Root Path Cost: 0; CIST Root Port: Po 1

 CIST Root Forward Delay: 15; Hello Time: 2; Max Age: 20; Max-hops: 19

 Configured Forward Delay: 15; Hello Time: 2; Max Age: 20; Max-hops: 20;

 Tx-HoldCount: 6

 Number of topology change(s): 62; Last change occurred 00:08:04 ago on Po 1

 

 Bpdu-guard errdisable timeout: disabled

 Bpdu-guard errdisable timeout interval: 300 sec

 Migrate Time: 3 sec

 

  Name                 : VCS_Fabric

  Revision Level : 10

  Digest                : 0x4D2251323BC0346C72288C0F541C3EAC

 

  Instance   VLAN

  --------        ----

   0:             10, 100-101, 104-106, 150, 200, 511

   1:             1, 501

   2:             502

 

 

VCS1# show spanning-tree mst brief              

 

 Spanning-tree Mode: Multiple Spanning Tree Protocol

 

 CIST Root ID                      Priority 0

                                              Address  0017.0fec.f800

 CIST Bridge ID                  Priority 32768

                                              Address  01e0.5200.0152

 CIST Regional Root ID   Priority 0

                                             Address  0017.0fec.f800

 

 Configured Hello Time 2, Max Age 20, Forward Delay 15

 Max Hops 20, Tx-HoldCount 6

 CIST Root  Hello Time 2, Max Age 20, Forward Delay 15, Max Hops 19

 CIST Root path cost 0

 

 Interface     Role  Sts     Cost       Prio  Link-type   Boundary  Edge

 -----------------------------------------------------------------------------------------

 Po 1          RTPT  FWD  1000       128   P2P           No               No 

 Po 2          DES   FWD   1000       128   P2P           No               No 

 

 

 Instance: 1; Vlans: 1, 501

 MSTI Root       Address  0017.0fec.f800   Priority  1

 MSTI Bridge     Address  01e0.5200.0152   Priority  32769

                 Root Port Po 1

 

 Interface     Role    Sts     Cost       Prio  Link-type   Boundary  Edge

 ----------------------------------------------------------------------------------------

 Po 1            RTPT  FWD  1000       128   P2P           No              No 

 Po 2            DES    FWD  1000       128   P2P           No              No 

 

 

 Instance: 2; Vlans: 502

 MSTI Root       Address  0019.0762.9800   Priority  2

 MSTI Bridge     Address  01e0.5200.0152   Priority  32770

                 Root Port Po 2

 

 Interface     Role    Sts     Cost       Prio  Link-type   Boundary  Edge

 ----------------------------------------------------------------------------------------

 Po 1          DES      FWD  1000       128   P2P           No              No 

 Po 2          RTPT    FWD  1000       128   P2P           No              No 

 

-------------------

 

MSTP Interoperability

VCS Fabric supports IEEE standard 802.1s MSTP as does Cisco Catalyst switches so Brocade VCS Fabric in MSTP mode can interoperate with Cisco switches in MSTP mode.

 

The VCS Fabric NOS command, cisco-interoperability, is required for certain legacy Cisco switches that do not conform to the IEEE 802.1s MSTP standard, These switches support “pre-standard” MSTP. This command shouldn’t be used to interoperate with Cisco switches conforming to standard IEEE 802.1s MSTP.

 

--NOS Commands-----------------

switch(config)#protocol spanning-tree mstp

switch(config-mstp)#cisco-interoperability enable 

-------------------

 

--Cisco Catalyst Commands-------

Cat6500-A#sh run

spanning-tree mode mst

spanning-tree vlan 501 priority 0

!        

spanning-tree mst configuration

 name VCS_Fabric

 revision 10

 instance 1 vlan 1, 501

 instance 2 vlan 502

!         

spanning-tree mst 0-1 priority 0

 

 

Cat6500-A#sh spanning-tree mst 1

 

##### MST1    vlans mapped:   1,501

Bridge        address 0017.0fec.f800  priority      1     (0 sysid 1)

Root          this switch for MST1

 

Interface        Role  Sts       Cost      Prio.Nbr     Type

---------------- ---- --- --------- --------    --------------------------------

Gi1/14           Desg FWD    20000    128.14       P2p

Te2/3             Desg FWD    2000      128.131    P2p

Po1                Desg FWD    1000      128.1665  P2p

 

 

VCS1# show spanning-tree mst instance 1 brief

 

 Instance: 1; Vlans: 1, 501

 MSTI Root         Address  0017.0fec.f800   Priority  1

 MSTI Bridge     Address  01e0.5200.0152   Priority  32769

                             Root Port Po 1

 

 Interface     Role    Sts     Cost       Prio  Link-type   Boundary  Edge

 ----------------------------------------------------------------------------------------

 Po 1            RTPT  FWD  1000       128   P2P           No               No 

 Po 2            DES    FWD  1000       128   P2P           No               No 

-------------------

 

RPVST+

 

Overview

RPVST+ protocol is IEEE standard 802.1w RSTP implementation on a per VLAN basis. RPVST+ protocol uses the RSTP state machine and has one instance of spanning tree for each VLAN on the switch. PVST+ is not a scalable model when there are many VLANs in the network, as it consumes a lot of CPU cycles. A reasonable compromise between the two extremes of RSTP and RPVST+ is MSTP.

 

Configurations

The following is the RPVST+ configuration and a sample output from its show command on VCS Fabric:

 

-------------------

A-VDX6730# show running-config protocol spanning-tree

protocol spanning-tree rpvst

!

A-VDX6730# show spanning-tree brief

VLAN 501

Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol

     Root ID       Priority 32768

                          Address 0017.0fec.f9f5

                          Hello Time 2, Max Age 20, Forward Delay 15

      Bridge ID   Priority 33269

                         Address 0005.33d3.e2ce

                         Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                         Migrate Time 3 sec

 

Interface     Role Sts      Cost       Prio Link-type  Edge

-----------------------------------------------------------------------

Te 0/5        RTPT FWD  2000       128   P2P          No

Te 0/6        ALT    DSC   2000       128   P2P          No

Te 0/9        DES   FWD  2000       128   P2P          No

      

VLAN 502     

Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol    

      Root ID      Priority 32768

                          Address 0017.0fec.f9f6

                          Hello Time 2, Max Age 20, Forward Delay 15     

      Bridge ID   Priority 33270

                          Address 0005.33d3.e2ce

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                           Migrate Time 3 sec

      

Interface     Role Sts      Cost      Prio Link-type    Edge

-----------------------------------------------------------------------

Te 0/5        RTPT FWD  2000      128   P2P           No

Te 0/6        ALT    DSC   2000     128   P2P            No

Te 0/9        DES   FWD  2000      128   P2P           No

-------------------

 

RPVST+ Interoperability

Brocade VCS Fabric support RPVST+, but RPVST is proprietary to Cisco and is not supported. To interoperate with Cisco Switches in RPVST+ mode, the following spanning-tree bpdu-mac command must be enabled in the interfaces that are connected to those Cisco switches. Otherwise, VCS Fabric and Cisco switches may have two different Root Bridges (as shown below) and RPVST+ does not operate correctly.

 

-------------------

switch(config)#interface Tengigabitethernet x/x

switch(conf-if-te-0/12)#spanning-tree bpdu-mac 0100.0ccc.cccd

-------------------

 

-------------------

VCS1# show spanning-tree vlan 501 brief

VLAN 501

 

 Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0017.0fec.f9f5

                          Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID   Priority 33269

                          Address 01e0.5200.0152

                          Root Port Po 1

                          Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                          Migrate Time 3 sec

 

 Interface     Role  Sts    Cost        Prio  Link-type   Edge

 ------------------------------------------------------------------------

 Po 1          RTPT  FWD  2000       128   P2P           No 

 Po 2          ALT     DSC   2000       128   P2P           No 

 

Cat6500-A#sh spanning-tree vlan 501

 

VLAN0501

  Spanning tree enabled protocol rstp

  Root ID    Priority    0

                    Address     0017.0fec.f9f5

                    This bridge is the root

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0   

                    Address     0017.0fec.f9f5

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                    Aging Time 300

 

Interface           Role    Sts     Cost    Prio.Nbr   Type

------------------- -------   -------  --------  ------------- --------------------------------

Gi1/14              Desg  FWD  4           128.14       P2p

Gi1/17              Desg  FWD  4           128.17       P2p

Te2/3                Desg  FWD  2           128.131    P2p

Po1                   Desg  FWD  1           128.1665  P2p

-------------------

 

Interoperability Test Results with Cisco Switches

This section provides interoperability test results with Cisco switches.

 

Interoperability Test Bed Diagram

The figure below shows a diagram of the STP interoperability test network topology.

 

 STPInteroperabilityTestBedNetwork.jpg

  STP Interoperability Test Bed Network

 

 

Interoperability Testing Methodology

The test network simulates existing customer infrastructure running STP. It consists of two Cisco Catalyst 6500 switches, and two Cisco Catalyst 3750 switches. The Cisco Catalyst 6500 switches are running IOS 122-33.SXI, and the Cisco Catalyst 3750 switches run IOS 15.0(1)SE or 12.2(46)SE.

 

VCS Fabric VCS1 is running NOS 4.0.x. It is connected to the Cisco network with STP configured. The VCS Fabric has two VDX8770s, two VDX 6730s, and two VDX 6720s. To form the VCS Fabric, RB11, RB12, RB1 and RB2 are connected to RB100 and RB101 via Brocade ISL trunks with 10 GbE links. Fabric VCS1 is connected to Cisco switches’ network via two 2x10GE links configured in LACP-based vLAGs (that is, port-channel 1 and port-channel 2) to ensure high availability for node and link failure. All vLAGs are enabled as Layer 2 trunks using 802.1Q (dot1q), allowing all VLAN traffic.

 

All interconnections between Cisco switches use 10GE or 1GE links and all the ports are enabled as Layer 2 trunk using 802.1Q (dot1q), allowing all VLAN traffic.

 

To simulate host and server traffic, flows are established using a Spirent Test Center (STC) tool. 300 Mbps traffic flows are sent on each STC port and distributed using full mesh with packet size of 128 bytes.

 

LAG Configurations

The following shows vLAG configuration for the VCS1 VCS Fabric and shows how to verify LAG state on the Brocade VDX Switches. The following reference contains more detail.

 

References

 

------------------

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no shutdown

 

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/34

interface TenGigabitEthernet 100/4/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 101/2/34

interface TenGigabitEthernet 101/2/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/33

interface TenGigabitEthernet 100/4/33

 no fabric isl enable

 no fabric trunk enable

 channel-group 2 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 101/2/33

interface TenGigabitEthernet 101/2/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 2 mode active type standard

 lacp timeout long

 no shutdown

-----------------------

 

802.1D STP Interoperability Test Result

 

Configurations

The following is the configuration used in the 802.1D STP interoperability test.

  • The 'protocol spanning-tree stp' command in the VCS Fabric enables 802.1.D STP.
  • The 'spanning-tree mode mst' command on the Cat6500-A, Cat6500-B, Cat3750-C, and Cat3750-D enables MSTP instance 0 which is the default instance for MSTP mode.
  • The 'spanning-tree mst 0 priority 0' command on the Cat6500-A makes this switch the Root Bridge.

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree stp

 

Cat6500-A#sh running-config | in spanning-tree

spanning-tree mode mst

spanning-tree mst 0 priority 0

 

!--- 'spanning-tree mst 0 priority 0' on Cat6500-A is set in an effort to secure the Root Bridge position.

 

Cat6500-B#sh running-config | in spanning-tree

spanning-tree mode mst

 

Cat3750-C#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

 

Cat3750-D#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

-------------------

 

Verification for Spanning Tree Topology

In the 802.1D STP interoperability test, Cat6500-A has lower bridge priority than other switches and it is elected as the Root Bridge. This caused port-channel 2 in the VCS Fabric and the GigE 1/0/15 port on the Cat3750-D to enter the Blocked state.

 

802.1DSTPTopology.jpg

   802.1D STP Topology

 

-------------------

VCS1# show spanning-tree brief

 

 Spanning-tree Mode: Spanning Tree Protocol

 

      Root ID      Priority 0

                         Address 0017.0fec.f800

                         Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

 

      Bridge ID    Priority 32768

                          Address 01e0.5200.0152

                          Root Port Po 1

                          Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface   Role     Sts   Cost       Prio  Link-type   Edge

 ---------------------------------------------------------------------

 Po 1          RTPT  FWD  2000     128   P2P            No 

 Po 2          ALT     BLK   2000     128   P2P            No 

 

!--- Port-channel 2 of the VCS Fabric is in the Blocked state. 

 

 

Cat6500-A#sh spanning-tree

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                   Address     0017.0fec.f800

                   This bridge is the root

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0      (priority 0 sys-id-ext 0)

                     Address     0017.0fec.f800

                      Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role Sts       Cost      Prio.Nbr    Type

------------------- ------  ------- ---------     -----------     --------------------------------

Gi1/14              Desg FWD  20000   128.14        P2p

Gi1/17              Desg FWD  20000   128.17        P2p

Te2/3               Desg FWD   2000     128.131      P2p

Po1                  Desg FWD  1000      128.1665   P2p Bound(STP)

 

 

Cat6500-B#sh spanning-tree

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                   Address     0017.0fec.f800

                   Cost        0

                    Port        131 (TenGigabitEthernet2/3)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

 

  Bridge ID  Priority    32768  (priority 32768 sys-id-ext 0)

             Address     0019.0762.9800

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role  Sts   Cost      Prio.Nbr       Type

------------------- -------  -----  ---------     -------------  --------------------------------

Gi1/14              Desg FWD   20000   128.14      P2p

Gi1/17              Desg FWD   20000   128.17      P2p

Te2/3               Root   FWD   2000     128.131    P2p

Po2                  Desg FWD  1000      128.1665   P2p Bound(STP)

 

 

Cat3750-D#sh spanning-tree

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                   Address     0017.0fec.f800

                   Cost        0

                   Port        14 (GigabitEthernet1/0/14)

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    32768  (priority 32768 sys-id-ext 0)

                     Address     001e.f711.0400

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role    Sts       Cost      Prio.Nbr  Type

------------------- -------    -------   ---------   -----------   --------------------------------

Gi1/0/14            Root    FWD   20000   128.14      P2p

Gi1/0/15            Altn      BLK    20000   128.15      P2p

Gi1/0/16            Desg  FWD    20000   128.16      P2p

 

!--- GigabitEthernet 1/0/15 of Cat3750-D is in the Blocked state. 

-------------------

 

Spanning Tree Convergence Time

In the 802.1D STP interoperability test, convergence time for a link or LAG failure and recovery from a link or LAG failures is about 30 seconds.

 

Test Result Summary

Based on verification of Spanning Tree topology and convergence time, the test result shows the 802.1D STP of Brocade VCS Fabric interoperates with MSTP instance 0 of Cisco Catalyst 6500 which is the default instance for MSTP, and that LAGs are treated as normal links in the 802.1D STP.

 

802.1w RSTP Interoperability Test Result

 

Configurations

The following is the configurations used in the 802.1w RSTP interoperability test.

  • The 'protocol spanning-tree rstp' command is configured on the VCS Fabric to enable the 802.1.D STP
  • The 'spanning-tree mode mst' command is configured on Cat6500-A , Cat6500-B, Cat3750-C, and Cat3750-D each to enable MSTP instance 0 which is default instance for the MSTP mode.
  • The 'spanning-tree mst 0 priority 0' command on Cat6500-A is set in make the switch the Root Bridge:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree rstp

 

Cat6500-A#sh running-config | in spanning-tree

spanning-tree mode mst

spanning-tree mst 0 priority 0

 

!--- 'spanning-tree mst 0 priority 0' on Cat6500-A is set in an effort to secure the Root Bridge position.

 

Cat6500-B#sh running-config | in spanning-tree

spanning-tree mode mst

 

Cat3750-C#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

 

Cat3750-D#sh run | in spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

-------------------

 

Verification of Spanning Tree Topology

The Cat6500-A switch has lower bridge priority than other switches and it is elected as the Root Bridge. This causes the VCS Fabric port-channel 2 and the Cisco network GigE 1/0/15 port in the Cat3750-D switch to enter the Discarded (Blocked) state.

 

802.1wRSTPTopology.jpg

   802.1w RSTP Topology

 

-------------------

VCS1# show spanning-tree brief                  

 

 Spanning-tree Mode: Rapid Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0017.0fec.f800

                           Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.


      Bridge ID    Priority 32768

                           Address 01e0.5200.0152

                           Root Port Po 1

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                         Migrate Time 3 sec

 

 Interface     Role    Sts      Cost       Prio  Link-type  Edge

 --------------------------------------------------------------------------

 Po 1            RTPT  FWD   2000       128   P2P          No 

 Po 2            ALT     DSC   2000        128   P2P          No 

 

!--- Port-channel 2 of the VCS Fabric is in the Discarded (Blocked) state. 

 

 

Cat6500-A#sh spanning-tree

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                   Address     0017.0fec.f800

                   This bridge is the root

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0      (priority 0 sys-id-ext 0)

                     Address     0017.0fec.f800

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role   Sts       Cost      Prio.Nbr      Type

------------------- -------   --------  --------     -------------   ------------------

Gi1/14              Desg   FWD   20000    128.14        P2p

Gi1/17              Desg   FWD   20000    128.17        P2p

Te2/3               Desg   FWD   2000       128.131      P2p

Po1                  Desg   FWD   1000       128.1665    P2p

 

 

Cat6500-B#sh spanning-tree                      

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                   Address     0017.0fec.f800

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

             Cost        0

             Port        131 (TenGigabitEthernet2/3)

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    32768  (priority 32768 sys-id-ext 0)

                     Address     0019.0762.9800

                      Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role   Sts       Cost        Prio.Nbr   Type

------------------- -------   -------  --------       ------------   -------------------

Gi1/14              Desg  FWD   20000     128.14       P2p

Gi1/17              Desg  FWD   20000     128.17       P2p

Te2/3               Root    FWD   2000       128.131     P2p

Po2                  Desg  FWD   1000       128.1665   P2p

 

 

Cat3750-D#sh spanning-tree

 

MST0

  Spanning tree enabled protocol mstp

  Root ID    Priority    0

                    Address     0017.0fec.f800

                    Cost        0

                    Port        14 (GigabitEthernet1/0/14)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

  Bridge ID  Priority    32768  (priority 32768 sys-id-ext 0)

                     Address     001e.f711.0400

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

Interface           Role   Sts        Cost      Prio.Nbr  Type

------------------- -------- --------- ----------   -----------   ---------------

Gi1/0/14            Root    FWD    20000   128.14    P2p

Gi1/0/15            Altn      BLK     20000   128.15    P2p

Gi1/0/16            Desg   FWD   20000   128.16    P2p

 

!--- GigabitEthernet 1/0/15 of Cat3750-D is in the Blocked state.

-------------------

 

Spanning Tree Convergence Time

In the 802.1w RSTP interoperability test, convergence time for a link or a LAG failure is about 150 msec, while convergence time for recovery from a link or LAG failure is about 300 msec.

 

Test Result Summary

The test shows the 802.1w RSTP in the Brocade VCS Fabric interoperates with the Cisco Catalyst switches and that LAGs are treated as a normal link in the 802.1w RSTP.

 

PVST+ Interoperability Test Result

 

Configurations

The following is the configuration used in the PVST+ interoperability test. Bridge priority is set to 0 for VLAN 501 on the VCS Fabric, and bridge priority is set to 0 for VLAN 502 on Cat6500-A.

 

  • The 'protocol spanning-tree pvst' command is configured in the VCS Fabric,
  • The 'spanning-tree mode pvst' command is configured on Cat6500-A, Cat6500-B,  Cat3750-C, and Cat3750-D each to enable PVST+.
  • The 'vlan 501 priority 0' command is set on the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.
  • The 'spanning-tree vlan 502 priority 0' command is set on Cat6500-A in an effort to secure the Root Bridge position for VLAN 502.
  • After 'protocol spanning-tree pvst' is configured on the VCS Fabric, the 'spanning-tree bpdu-mac 0100.0ccc.cccd' command must be configured on the VCS Fabric interfaces connected to the Catalyst 6500 switches:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree pvst

 vlan 501 priority 0

 

!--- 'vlan 501 priority 0' is set on the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.

 

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown


!--- To interoperate with Cisco Switches in PVST+ mode, this must be configured in the interfaces that are connected to those Cisco Switches.


Cat6500-A#sh run | in spanning-tree

spanning-tree mode pvst

spanning-tree vlan 502 priority 0

 

!--- 'spanning-tree vlan 502 priority 0' is set on Cat6500-A in an effort to secure the Root Bridge position for VLAN 502.

-------------------

 

 

Verification of Spanning Tree Topology

 

VLAN 501

For VLAN 501, the VCS Fabric is seen as a single logical switch that has a bridge priority that is lower than all the other switches and it is elected as the Root Bridge. Therefore, the TenGi 2/3 interface of Cat6500-B and the Gig 1/0/15 interface of Cat3750-D are in the Blocked state.

 

PVST+TopologyforVLAN502.jpg 

   PVST+ Topology for VLAN 501

 

-------------------

VCS1# show spanning-tree vlan 501 brief

VLAN 501

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 501

                          Address 01e0.5200.0152

                          Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 501

                           Address 01e0.5200.0152

                        Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface   Role  Sts     Cost       Prio    Link-type   Edge

 ------------------------------------------------------------------------

 Po 1          DES   FWD  2000       128   P2P            No 

 Po 2          DES   FWD  2000       128   P2P            No 

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

 

Cat6500-A#sh spanning-tree vlan 501 

 

VLAN0501

  Spanning tree enabled protocol ieee

  Root ID    Priority    501

                   Address     01e0.5200.0152

                    Cost        1

                   Port        1665 (Port-channel1)

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    32768

                     Address     0017.0fec.f9f5

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                      Aging Time 300

 

Interface           Role   Sts       Cost   Prio.Nbr     Type

------------------- -------- --------- -------- -------------   -----------------

Gi1/14              Desg   FWD   4         128.14        P2p

Gi1/17              Desg   FWD   4         128.17        P2p

Te2/3               Desg   FWD    2         128.131     P2p

Po1                  Root    FWD    1         128.1665   P2p

 

 

Cat6500-B#sh spanning-tree vlan 501

 

VLAN0501

  Spanning tree enabled protocol ieee

  Root ID    Priority    501

                    Address     01e0.5200.0152

                     Cost        1

                    Port        1665 (Port-channel2)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    32768

                     Address     0019.0762.99f5

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                     Aging Time 300

 

Interface           Role  Sts       Cost    Prio.Nbr     Type

------------------- -------  --------- --------  --------------  ----------------

Gi1/14              Desg FWD    4          128.14        P2p

Gi1/17              Desg FWD    4          128.17        P2p

Te2/3               Altn     BLK     2          128.131      P2p

Po2                  Root   FWD    1          128.1665   P2p

 

 

Cat3750-D#sh spanning-tree vlan 501

 

VLAN0501

  Spanning tree enabled protocol ieee

  Root ID    Priority    501

                    Address     01e0.5200.0152

                    Cost        5

                    Port        14 (GigabitEthernet1/0/14)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    33269  (priority 32768 sys-id-ext 501)

                     Address     001e.f711.0400

                      Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                      Aging Time 300

 

Interface           Role     Sts       Cost   Prio.Nbr      Type

------------------- --------   --------- -------- --------------  -----------------

Gi1/0/14            Root    LIS        4         128.14        P2p

Gi1/0/15            Altn      BLK      4         128.15        P2p

Gi1/0/16            Desg   LIS        4         128.16       P2p

 

-------------------

 

VLAN 502

For VLAN 502, the Cat6500-A switch has a bridge priority that is lower than all the other switches, and it is elected as the Root Bridge. Therefore, port-channel 2 in the VCS Fabric and the Gig 1/0/15 interface in the Cat3750-D switch are in Blocked state.

 

PVST+TopologyforVLAN502.jpg

   PVST+ Topology for VLAN 502

 

-------------------

VCS1# show spanning-tree vlan 502 br

VLAN 502

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0017.0fec.f9f6

                          Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

 

      Bridge ID    Priority 33270

                           Address 01e0.5200.0152

                           Root Port Po 1

                            Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface   Role    Sts     Cost     Prio  Link-type  Edge

 ---------------------------------------------------------------------

 Po 1          RTPT  FWD  2000     128   P2P           No 

 Po 2          ALT     BLK   2000      128   P2P           No 

 

 

Cat6500-A#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol ieee

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

                    This bridge is the root

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0   

                    Address     0017.0fec.f9f6

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                  Aging Time 300

 

Interface           Role    Sts       Cost   Prio.Nbr  Type

------------------- ---- --   --------- -------- ------------  -------------------

Gi1/14              Desg   FWD   4         128.14      P2p

Gi1/17              Desg   FWD   4         128.17      P2p

Te2/3               Desg   FWD   2         128.131     P2p

Po1                  Desg   FWD   1         128.1665  P2p

 

 

Cat3750-D#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol ieee

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

                    Cost        6

                    Port        14 (GigabitEthernet1/0/14)

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

 

  Bridge ID  Priority    33270  (priority 32768 sys-id-ext 502)

                     Address     001e.f711.0400

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                    Aging Time 300

 

Interface           Role    Sts       Cost   Prio.Nbr  Type

------------------- --------   -------   -------- -----------  -------------------

Gi1/0/14            Root    FWD    4         128.14     P2p

Gi1/0/15            Altn      BLK     4         128.15     P2p

Gi1/0/16            Desg  FWD    4         128.16     P2p

------------------

 

Spanning Tree Convergence Time

In the test configuration, the convergence time for a link or a LAG failure is of about 30 seconds, and the convergence time for recovery from a link f or the LAG failure is about 33 seconds.

 

Test Result Summary

The test result shows PVST+ in the Brocade VCS Fabric interoperates with the Cisco Catalyst switches and that LAGs are treated as normal links in the PVST+.

 

MSTP Interoperability Test Result

 

Configurations

The following is the configurations used in the MSTP interoperability test, and 3 MSTP instances, including default instance 0, are enabled on the VCS Fabric and Cisco Catalyst Switches.

  • The 'protocol spanning-tree mstp' command is configured on the VCS Fabric to enable MSTP.
  • Instance 1 for VLAN 1 and 501, instance 2 for VLAN 502, a region of VCS_Fabric and a revision of 10 are configured.
  • The 'instance 1 priority 0' command in the VCS Fabric is used in an effort to secure the Root Bridge position for MSTP instance 1,
  • The 'spanning-tree mst 2 priority 0' command is configured on the Cat6500-A switch in an effort to secure the Root Bridge for MSTP instance 2:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree mstp

 instance 1 vlan 501

 instance 1 priority 0

 

!--- This is configured in an effort to secure the Root Bridge position for MSTP instance 1.


  instance 2 vlan 502

  region VCS_Fabric

  revision 10

 

 

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 no shutdown

!

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 no shutdown

 

Cat6500-A#sh run | be spanning-tree

spanning-tree mode mst

!

spanning-tree mst configuration

 name VCS_Fabric

 revision 10

 instance 1 vlan 501

 instance 2 vlan 502

!

spanning-tree mst 2 priority 0

 

!--- This is configured in an effort to secure the Root Bridge for MSTP instance 2.

 

Cat6500-B#sh run | be spanning-tree

spanning-tree mode mst

!

spanning-tree mst configuration

 name VCS_Fabric

 revision 10

 instance 1 vlan 501

 instance 2 vlan 502

 

Cat3750-C#sh run | be spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

!

spanning-tree mst configuration

 name VCS_Fabric

 revision 10

 instance 1 vlan 501

 instance 2 vlan 502

 

Cat3750-D#sh run | be spanning-tree

spanning-tree mode mst

spanning-tree extend system-id

!

spanning-tree mst configuration

 name VCS_Fabric

 revision 10

 instance 1 vlan 501

 instance 2 vlan 502

-------------------

 

Verification of Spanning Tree Topology

 

MSTP instance 1

The VCS Fabric appears as a single logical switch and has a bridge priority that is lower than all the other switches, so it is elected as the Root Bridge. The Tengig 2/3 interface of the Cat6500-B switch and the Gig 1/0/15 interface of the Cat3750-D switch are in the Blocked.

 

MSTPInstance1Topology.jpg

   MSTP Instance 1 Topology=

 

-------------------

VCS1# show spanning-tree mst instance 1 brief

 

 Instance: 1; Vlans:  501

 MSTI Root       Address  01e0.5200.0152   Priority  1

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

 MSTI Bridge     Address  01e0.5200.0152   Priority  1

 

 Interface     Role   Sts    Cost         Prio  Link-type    Boundary  Edge

 -----------------------------------------------------------------------------------------

 Po 1            DES   FWD  2000       128   P2P             No              No 

 Po 2            DES   FWD  2000       128   P2P             No              No 

 

 

Cat6500-A#sh spanning-tree  mst 1

 

##### MST1    vlans mapped:   501

Bridge        address 0017.0fec.f800  priority      32769 (32768 sysid 1)

Root           address 01e0.5200.0152  priority      1     (0 sysid 1)

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

            port    Po1             cost      1000                 rem hops 19

 

Interface        Role   Sts     Cost      Prio.Nbr     Type

---------------- -------- --------- ---------   --------------------------------

Gi1/14           Desg   FWD  20000    128.14      P2p

Gi1/17           Desg   FWD  20000    128.17      P2p

Te2/3            Desg   FWD   2000      128.131    P2p

Po1               Root    FWD   1000      128.1665  P2p

 

Cat6500-B#sh spanning-tree mst 1

 

##### MST1    vlans mapped:   501

Bridge        address 0019.0762.9800  priority      32769 (32768 sysid 1)

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

Root          address 01e0.5200.0152  priority      1     (0 sysid 1)

            port    Po2             cost      1000                 rem hops 19

 

Interface        Role   Sts    Cost       Prio.Nbr      Type

---------------- --------  -------  ---------   --------------   --------------------------------

Gi1/14           Desg  FWD   20000   128.14        P2p

Gi1/17           Desg  FWD   20000   128.17        P2p

Te2/3            Altn      BLK    2000     128.131       P2p

Po2               Root    FWD   1000     128.1665    P2p

 

Cat3750-C#sh spanning-tree mst 1

 

##### MST1    vlans mapped:   501

Bridge        address 001b.d406.bb80  priority      32769 (32768 sysid 1)

Root           address 01e0.5200.0152  priority      1     (0 sysid 1)

              port    Gi1/0/14        cost          21000     rem hops 18

 

Interface        Role   Sts       Cost         Prio.Nbr  Type

----------------   ------- --------- ----------    ------------  ------------------

Gi1/0/14         Root    FWD   20000     128.14     P2p

Gi1/0/15         Desg   FWD   20000     128.15     P2p

Gi1/0/16         Desg   FWD   20000     128.16     P2p

 

Cat3750-D#sh spanning-tree mst 2

 

##### MST2    vlans mapped:   502

Bridge        address 001e.f711.0400  priority      32770 (32768 sysid 2)

Root           address 0017.0fec.f800  priority      2     (0 sysid 2)

              port    Gi1/0/14        cost          22000     rem hops 18

 

Interface        Role    Sts        Cost      Prio.Nbr  Type

---------------- ---------  ---------  ---------   -----------  --------------------

Gi1/0/14        Root     FWD     20000   128.14   P2p

Gi1/0/15        Altn       BLK      20000   128.15   P2p

Gi1/0/16        Desg    FWD     20000   128.16   P2p

-------------------

 

MSTP instance 2

The VDX6730-A switch has a lower bridge priority than other switches, so it is elected as the Root Bridge. The port-channel 2 of the VCS Fabric and the Gig 1/0/15 interface of Cat3750-D switch are in the Blocked state.

 

MSTPInstance2Topology.jpg

   MSTP Instance 2 Topology

 

-------------------

VCS1# show spanning-tree mst instance 2 brief

 

 Instance: 2; Vlans: 502

 MSTI Root       Address  0017.0fec.f800   Priority  2

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

 MSTI Bridge     Address  01e0.5200.0152   Priority  32770

                 Root Port Po 1

 

 Interface   Role    Sts    Cost       Prio  Link-type   Boundary  Edge

 --------------------------------------------------------------------------------------

 Po 1          RTPT  FWD  2000      128   P2P           No               No 

 Po 2          ALT     DSC   2000      128   P2P           No               No 

 

!--- Po2 of the VCS Fabric is in the Discarded state (that is, Blocked state).

 

 

Cat6500-A#sh spanning-tree  mst 2

 

##### MST2    vlans mapped:   502

Bridge        address 0017.0fec.f800  priority      2     (0 sysid 2)

Root          this switch for MST2

 

Interface       Role    Sts      Cost      Prio.Nbr      Type

---------------- --------  --------- --------     -----------     ---------------------

Gi1/14           Desg   FWD   20000    128.14       P2p

Gi1/17           Desg   FWD   20000    128.17       P2p

Te2/3            Desg   FWD    2000      128.131    P2p

Po1               Desg   FWD   1000       128.1665  P2p

 

 

Cat6500-B#sh spanning-tree mst 2

 

##### MST2    vlans mapped:   502

Bridge        address 0019.0762.9800  priority      32770 (32768 sysid 2)

Root           address 0017.0fec.f800  priority      2     (0 sysid 2)

            port    Te2/3           cost      2000                 rem hops 19

 

Interface        Role    Sts      Cost      Prio.Nbr     Type

---------------- -------   --------   --------    ------------    -----------------

Gi1/14           Desg   FWD   20000   128.14       P2p

Gi1/17           Desg   FWD   20000   128.17       P2p

Te2/3            Root     FWD   2000      128.131    P2p

Po2               Desg    FWD   1000     128.1665  P2p

 

 

Cat3750-C#sh spanning-tree mst 2

 

##### MST2    vlans mapped:   502

Bridge        address 001b.d406.bb80  priority      32770 (32768 sysid 2)

Root           address 0017.0fec.f800  priority      2     (0 sysid 2)

              port    Gi1/0/14        cost          20000     rem hops 19

 

Interface        Role    Sts       Cost    Prio.Nbr  Type

---------------- -------    ---------  --------  -----------  -------------------

Gi1/0/14       Root     FWD    20000  128.14   P2p

Gi1/0/15       Desg    FWD   20000   128.15   P2p

Gi1/0/16       Desg    FWD   20000   128.16   P2p

 

 

Cat3750-D#sh spanning-tree mst 2

 

##### MST2    vlans mapped:   502

Bridge        address 001e.f711.0400  priority      32770 (32768 sysid 2)

Root           address 0017.0fec.f800  priority      2     (0 sysid 2)

              port    Gi1/0/14        cost          22000     rem hops 18

 

Interface      Role     Sts      Cost       Prio.Nbr  Type

---------------- ------     -------   --------     ----------   ---------------------

Gi1/0/14       Root    FWD    20000   128.14     P2p

Gi1/0/15       Altn      BLK     20000    128.15    P2p

Gi1/0/16       Desg   FWD    20000   128.16    P2p

 

!--- Gi 1/0/15 of Cat3750-D is in the Blocked state.

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or a LAG failure is about 200 msec, and convergence time for recovery from a link for LAG failure is about 290 msec.

 

Test Result Summary

The the test result shows that MSTP in Brocade VCS Fabric interoperates with Cisco Catalyst switches, and that LAGs are treated as normal links in the MSTP.

 

RPVST+ Interoperability Test Result

 

Configurations

The following is the configuration used in the RPVST+ interoperability test.

  • The 'protocol spanning-tree rpvst' command is configured on the VCS Fabric to enable PVST+,
  • The 'spanning-tree mode rapid-pvst' command is configured on Cat6500-A and Cat6500-B switches to enable RPVST+.
  • The 'vlan 501 priority 0' command is set in the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.
  • The 'spanning-tree vlan 502 priority 0' command is set on Cat6500-A switch in an effort to secure the Root Bridge position for VLAN 502.
  • After 'protocol spanning-tree pvst' is configured on the VCS Fabric, the 'spanning-tree bpdu-mac 0100.0ccc.cccd' command must be configured on the VCS Fabric interfaces connected to the Catalyst 6500 switches:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree rpvst

 vlan 501 priority 0

 

!--- This is configured in an effort to secure the Root Bridge position for VLAN 501 and 503.

 

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

Cat6500-A#sh running-config | in spanning-tree

spanning-tree mode rapid-pvst

spanning-tree vlan 502 priority 0

 

!--- This is configured in an effort to secure the Root Bridge position for VLAN 502.

 

 

Cat6500-B#sh running-config | in spanning-tree

spanning-tree mode rapid-pvst

 

 

Cat3750-C#sh run | in spanning-tree

spanning-tree mode rapid-pvst

spanning-tree extend system-id

 

 

Cat3750-D#   sh run | in spanning-tree

spanning-tree mode rapid-pvst

spanning-tree extend system-id

-------------------

 

Verification of Spanning Tree Topology

 

VLAN 501

For VLAN 501, the VCS Fabric has a lower bridge priority than the other switches so is elected to the Root Bridge. Therefore, the TenGi 2/3 interface of Cat6500-B switch and the Gig 1/0/15 interface of the Cat3750-D switch are in the Discarding (Blocked) state.

 

RPVST+TopologyforVLAN501.jpg 

   RPVST+ Topology for VLAN 501

 

VLAN 502

For VLAN 502, the Cat6500-A switch has a lower bridge priority than the other switches so it is elected the Root Bridge. Therefore, the Port-channel 2 interface of VCS Fabric and the Gig 1/0/15 interface of Cat3750-D switch are in Discarding (Blocked) state.

 

RPVST+TopologyforVLAN502.jpg 

   RPVST+ Topology for VLAN 502

 

-------------------

VCS1# show spanning-tree vlan 502 br

VLAN 502

 

 Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                         Address 0017.0fec.f9f6

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

                           Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 33270

                           Address 01e0.5200.0152

                           Root Port Po 1

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                          Migrate Time 3 sec

 

 Interface   Role    Sts     Cost       Prio  Link-type   Edge

 --------------------------------------------------------------------------

 Po 1          RTPT  FWD   2000     128   P2P             No 

 Po 2          ALT      DSC  2000     128    P2P             No 

 

!--- Port-channel 2 (that is, vLAG) of the VCS Fabric is in the Blocked state.

 

Cat6500-A#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol rstp

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

                    This bridge is the root

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    0   

                     Address     0017.0fec.f9f6

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                  Aging Time 300

 

Interface           Role    Sts       Cost  Prio.Nbr     Type

------------------- -------   --------- -------- ------------    ------------------

Gi1/14              Desg   FWD    4         128.14       P2p

Gi1/17              Desg   FWD    4         128.17       P2p

Te2/3               Desg   FWD    2         128.131     P2p

Po1                  Desg   FWD    1         128.1665   P2p

 

 

Cat6500-B#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol rstp

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

 

!--- This is the MAC address of the Cat6500-A, the Root Bridge.

 

                    Cost        2

                    Port        131 (TenGigabitEthernet2/3)

                   Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    32768

                     Address     0019.0762.99f6

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                      Aging Time 300

 

Interface          Role      Sts       Cost   Prio.Nbr     Type

------------------- -------    --------- --------  -----------     -------------------

Gi1/14              Desg    FWD    4         128.14         P2p

Gi1/17              Desg    FWD    4         128.17         P2p

Te2/3                Root     FWD    2         128.131       P2p

Po2                   Desg    FWD    1         128.1665    P2p

 

Cat3750-C#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol rstp

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

                    Cost        4

                    Port        14 (GigabitEthernet1/0/14)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    33270  (priority 32768 sys-id-ext 502)

                     Address     001b.d406.bb80

                     Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                  Aging Time  300 sec

 

Interface           Role    Sts      Cost    Prio.Nbr Type

------------------- --------  --------- -------- ----------   --------------------

Gi1/0/14           Root    FWD    4         128.14    P2p

Gi1/0/15           Desg   FWD    4         128.15    P2p

Gi1/0/16           Desg   FWD    4         128.16    P2p

 

Cat3750-D#sh spanning-tree vlan 502

 

VLAN0502

  Spanning tree enabled protocol rstp

  Root ID    Priority    0

                    Address     0017.0fec.f9f6

                    Cost        6

                    Port        14 (GigabitEthernet1/0/14)

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

 

  Bridge ID  Priority    33270  (priority 32768 sys-id-ext 502)

                    Address     001e.f711.0400

                    Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

                    Aging Time 300

 

Interface           Role    Sts       Cost      Prio.Nbr   Type

------------------- -------   --------- --------  --------------  ----------------

Gi1/0/14           Root    FWD    4         128.14          P2p

Gi1/0/15           Altn      BLK     4         128.15          P2p

Gi1/0/16           Desg   FWD    4         128.16         P2p

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or a LAG failure in the VCS Fabric is of about 200 msec, and convergence time for recovery from a link or the LAG failure is about 290 msec.

 

Test Result Summary

The test result shows RPVST+ in a Brocade VCS Fabric interoperates with a Cisco Catalyst 6500 switch, and that LAGs are treated as normal links in the RPVST+.

 

Interoperability Test Results with Brocade MLX

This section tests interoperability of NOS 4.0.x STP i with Brocade MLX routers.

 

Interoperability Test Topology

The figure below shows the STP interoperability test network topology.

 

MLXSTPInteroperabilityTestBedNetwork.jpg

   MLX STP Interoperability Test Bed Network

 

 

Interoperability Test Methodology

The MLXe-A router simulates existing customer infrastructure running STP, with Brocade MLX NI 5.5c release firmware.

 

VCS1 simulates a VCS Fabric with NOS 4.0 running STP. It has six VDX Switches (2 VDX8770s, 2 VDX 6730s, and 2 VDX 6720s). To form the VCS Fabric, RB11, RB12, RB1 and RB2 are connected to RB100 and RB101 via Brocade ISL trunks using 10 GbE links. VCS1 is connected to the MLXe-A router via 2x10GE links that are configured in a LACP-based vLAG (port-channel 101) to ensure high availability for multiple node and link failures. All vLAGs are enabled as Layer 2 trunks using 802.1Q (dot1q) allowing all VLANs. All the other ports are enabled as Layer 2 trunks using 802.1Q (dot1q) allowing all VLANs.

 

To simulate host and server traffic, flows are established using the Spirent Test Center (STC) tool. 300 Mbps traffic flows are sent on each STC port and distributed using full mesh with a packet size of 128 bytes.

 

LAG Configurations

The following is the VCS Fabric vLAG. For details about how to design vLAGs and how to verify vLAG state on Brocade VDX Switches, please see the following reference.

 

References

 

------------------

VCS1# show running-config interface Port-channel 101

interface Port-channel 101

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/35

interface TenGigabitEthernet 100/4/35

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 101/2/35

interface TenGigabitEthernet 101/2/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

telnet@MLXe-A#sh run

lag "To-VCS1" dynamic id 3

 ports ethernet 1/1 ethernet 1/3

 primary-port 1/1

 deploy

-----------------------

 

802.1D STP Interoperability Test Result

 

Configurations

The following is the configuration used in the 802.1D STP interoperability test.

  • The 'protocol spanning-tree stp' command is configured on VCS Fabric to enable the 802.1D STP.
  • The 'spanning-tree single' command is configured on MLXe-A router to enable the 802.1D STP.
  • The 'spanning-tree single priority 0' command on MLXe-A router is used in an effort to secure the Root Bridge position:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree stp

 

 

 

telnet@MLXe-A#sh run

spanning-tree single

 

!---Single spanning tree which is the 802.1D STP is enabled, and it run Single Spanning Tree across all of its ports and VLANs. However, when ‘spanning-tree single’ is globally enabled, by default, no VLAN is added to the Single Spanning Tree, and therefore, ‘spanning-tree’ must be enabled on the VLANs to add them to Single Spanning Tree.   

!

!

 spanning-tree single priority 0

 

!--- 'spanning-tree single0 priority 0' on MLXe-A is set in an effort to secure the Root Bridge position.

 

 

!

no dual-mode-default-vlan                                        

!                                                                

!                                                                 

vlan 1 name DEFAULT-VLAN                                         

 no untagged ethe 1/1 to 1/3 ethe 6/4                            

 spanning-tree

 

!--- To add the VLAN 1 to Single Spanning Tree, ‘spanning-tree’ is enabled.                                                  

!                                                                

vlan 501                                                         

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

 spanning-tree 

 

!--- To add the VLAN 501 to Single Spanning Tree, ‘spanning-tree’ is enabled.                                              

!                                                                

vlan 502                                                         

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

 spanning-tree 

 

!--- To add the VLAN 502 to Single Spanning Tree, ‘spanning-tree’ is enabled.             

-------------------

 

Verification for Spanning Tree Topology

MLXe-A has a lower bridge priority than the other switches and it is elected as the Root Bridge. The TenGig 100/4/36 interface of the VCS Fabric is in the Blocked state.

 

MLX802.1DSTPTopology.jpg

  MLX 802.1D STP Topology

 

-------------------

VCS1# show spanning-tree brief

 

 Spanning-tree Mode: Spanning Tree Protocol

 

      Root ID      Priority 0

                         Address 0024.3899.fb00

                          Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the MLXe-A, the Root Bridge.

 

      Bridge ID    Priority 32768

                           Address 01e0.5200.01c2

                           Root Port Po 101

                           Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface          Role   Sts     Cost        Prio  Link-type   Edge

 ------------------------------------------------------------------------------

 Te 100/4/36   ALT     BLK    2000       128   P2P           No 

 Po 101           RTPT  FWD   2000       128   P2P           No 

 

 

telnet@MLXe-A#sh spanning-tree

 

VLAN 4095 - STP instance 0

--------------------------------------------------------------------

STP Bridge Parameters:

 

Bridge                    Bridge  Bridge  Bridge   Hold   LastTopology   Topology

Identifier               MaxAge  Hello   FwdDly  Time   Change             Change

hex                             sec     sec      sec        sec      sec                     cnt

000000243899fb00 20     2           15          1          345                    15     

 

RootBridge                  RootPath  DesignatedBridge       Root  Max   Hel    Fwd

Identifier                       Cost           Identifier                        Port   Age    lo       Dly

hex                                                    hex                                            sec    sec   sec

000000243899fb00    0                000000243899fb00   Root   20      2      15 

 

!--- This is the MAC address of the MLXe-A, the Root Bridge.

 

STP Port Parameters:

 

Port  Prio Path     State                    Designat-   Designated                Designated

Num rity   Cost                                  ed Cost      Root                             Bridge

1/1   128    2         FORWARDING   0                 000000243899fb00  000000243899fb00

1/2   128    2         FORWARDING   0                 000000243899fb00  000000243899fb00

1/3   128    2         FORWARDING   0                 000000243899fb00  000000243899fb00

6/4   128    4         FORWARDING   0                 000000243899fb00  000000243899fb00

 

!--- These path cost values shows MLX uses “short mode” STP port cost by default.

 

SSTP members: 1 501 to 502

 

!--- It shows VLAN 1, VLAN 501, and VLAN 502 are added to Single Spanning Tree Protocol.

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or  LAG failure is about 30 seconds, and convergence time for recovery from a link or LAG failure is about 30 seconds.

 

Test Result Summary

The test result shows 802.1D STP in a Brocade VCS Fabric interoperates with the 802.1D Single Spanning Tree (SSTP) of a Brocade MLX router, and that LAGs are treated as normal links in the 802.1D STP.

 

802.1w RSTP Interoperability Test Result

 

Configurations

The following is the configuration used in the 802.1w RSTP interoperability test.

  • The 'protocol spanning-tree rstp' command is configured on the VCS Fabric to enable the 802.1.D STP.
  • The 'rstp single' command is configured on the MLXe-A router to enable Single RSTP.
  • The 'rstp single priority 0' command is configured on the MLXe-A router in an effort to secure the Root Bridge position:

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree rstp

 

 

telnet@MLXe-A#sh run

rstp single

 

!--- ‘rstp single’ globally enables 802.1w Single Rapid spanning tree for all ports and VLANs.  However, when ‘rstp single’ is globally enabled, by default, no VLAN is added to the Single Rapid Spanning Tree, and therefore, ‘spanning-tree’ must be enabled on the VLANs to add them to Single Rapid Spanning Tree.   

 

!

 rstp single priority 0

!--- 'rstp single priority 0' on MLXe-A is set in an effort to secure the Root Bridge position.

 

!

no dual-mode-default-vlan                                        

!                                                                

!                                                                

vlan 1 name DEFAULT-VLAN                                         

 no untagged ethe 1/1 to 1/3 ethe 6/4                             

 spanning-tree 

 

!--- To add the VLAN 1 to Single Spanning Tree, ‘spanning-tree’ is enabled.                                          

!

vlan 501

 tagged ethe 1/1 to 1/3 ethe 6/4

 spanning-tree

 

!--- To add the VLAN 501 to Single Spanning Tree, ‘spanning-tree’ is enabled.

!

vlan 502

 tagged ethe 1/1 to 1/3 ethe 6/4

 spanning-tree

 

!--- To add the VLAN 502 to Single Spanning Tree, ‘spanning-tree’ is enabled.

-------------------

 

Verification of Spanning Tree Topology

The MLXe-A router has a lower bridge priority than the other switches and is elected the Root Bridge. The TeGig 100/4/36 interface of VCS Fabric is in the Discarded (Blocked).

 

MLX802.1wRSTPTopology.jpg

   MLX 802.1w RSTP Topology

 

-------------------

VCS1# show spanning-tree brief

 

 Spanning-tree Mode: Rapid Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0024.3899.fb20

                          Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the MLXe-A, the Root Bridge.

 

      Bridge ID    Priority 32768

                           Address 01e0.5200.01c2

                           Root Port Po 101

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                          Migrate Time 3 sec

 

 Interface         Role     Sts       Cost        Prio  Link-type  Edge

 -------------------------------------------------------------------------------

 Te 100/4/36   ALT       DSC    2000       128   P2P          No 

 Po 101            RTPT   FWD    2000       128   P2P          No 

 

!--- TenGig 100/4/36 of the VCS Fabric is in the Discarded (Blocked) state. 

 

 

telnet@MLXe-A#sh rstp

 

VLAN 4095 - RSTP instance 0

--------------------------------------------------------------------

RSTP (IEEE 802.1w) Bridge Parameters:

 

Bridge                             Bridge     Bridge    Bridge    Force          tx

Identifier                         MaxAge    Hello    FwdDly    Version       Hold

hex                                  sec           sec        sec                               cnt

000000243899fb20    20              2            15            Default        3   

 

RootBridge                  RootPath  DesignatedBridge     Root      Max  Hel   Fwd

Identifier                       Cost           Identifier                      Port       Age   lo      Dly

hex                                                    hex                                             sec   sec    sec

000000243899fb20  0                  000000243899fb20  Root     20    2         15 

 

RSTP (IEEE 802.1w) Port Parameters:

 

      <--- Config Params -->|<-------------- Current state ----------------->

Port    Pri    PortPath  P2P  Edge  Role                   State                    Designa-  Designated

Num           Cost         Mac  Port                                                              ted cost     bridge

1/1      128 2000        F        F         DESIGNATED  FORWARDING   0                 000000243899fb20 

1/2     128  2000        F        F         DESIGNATED  FORWARDING   0                 000000243899fb20 

1/3     128  2000        F        F         DESIGNATED  FORWARDING   0                 000000243899fb20 

6/4     128  20000     F        F         DESIGNATED  FORWARDING    0                000000243899fb20

 

!--- These path cost values shows MLX uses “long mode” STP port cost by default in Single Rapid Spanning Tree Protocol.

 

SSTP members: 1 501 to 502

 

!--- It shows VLAN 1, VLAN 501, and VLAN 502 are added to Single Rapid Spanning Tree Protocol.

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or LAG failure is about 200 msec, and convergence time for the recovery from a link failure or LAG failure is about 280 msec.

 

Test Result Summary

The test result shows 802.1w RSTP in a Brocade VCS Fabric interoperates with a Brocade MLX router and that LAGs are treated as a normal link in the 802.1w RSTP.

 

PVST+ Interoperability Test Result

 

Configurations

The following is the configuration used in the PVST+ interoperability test.

  • Bridge priority is set to 0 for VLAN 501 on the VCS Fabric,
  • Bridge priority is set to 0 for VLAN 502 on MLXe-A router.
  • The 'protocol spanning-tree pvst' command is configured on the VCS Fabric
  • The 'spanning-tree' command is configured on MLXe-A router to enable PVST+
  • The 'vlan 501 priority 0' command is set on the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.
  • The 'spanning-tree priority 0' command is set for VLAN 502 on MLXe-A router in an effort to secure the Root Bridge for VLAN 502.
  • After the 'protocol spanning-tree pvst' command is configured on the VCS Fabric, the 'spanning-tree bpdu-mac 0100.0ccc.cccd' command must be configured on the VCS Fabric interfaces that connect to the MLXe-A router.

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree pvst

 vlan 501 priority 0

 

!--- 'vlan 501 priority 0' is set on the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.

 

VCS1# show running-config interface Port-channel 101

interface Port-channel 101

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/36

interface TenGigabitEthernet 100/4/36

 fabric isl enable

 fabric trunk enable

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

!--- To interoperate with MLX  in PVST+ mode, this must be configured in the interfaces that are connected to the MLX.

 

 

telnet@MLXe-A#sh run

!

spanning-tree

 

!--- Brocade’s multiple instances of spanning tree is globally configured on the MLXe-A, so each VLAN on MLX runs a separate spanning tree instance. On the MLX-A receiving PVST BPDU on these ports, PVST mode is automatically enabled as shown in the output of ‘sh spanning-tree pvst-mode’ below, and therefore, no additional command is required to interoperate with VCS’ PVST+ in the setup.

 

!

no dual-mode-default-vlan

!

!                                                                

vlan 1 name DEFAULT-VLAN                                         

 no untagged ethe 1/1 to 1/3 ethe 6/4   

 

!--- As “dual-mode-default-vlan” is disabled in the setup, untagged VLAN 1 (that is, default VLAN)  runs Spanning Tree on all of its ports other than the tagged ports, eth 1/1, eth 1/2, eth 1/3, and eth 6/4.

 

Note:  If “dual-mode-default-vlan” is enabled,  tagged ports will be included in VLAN 1 as untagged ports as well, and therefore, untagged VLAN1 (that is, default VLAN) will run Spanning Tree on all of its ports including those tagged ports, eth 1/1, eth 1/2, eth 1/3, and eth 6/4.

 

 !                                                         

vlan 501                                                         

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

!                                                                

vlan 502                                                         

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

 spanning-tree priority 0                                         

                                

!--- 'spanning-tree priority 0' under vlan 502 is set on MLX in an effort to secure the Root Bridge position for VLAN 502.

 

telnet@MLXe-A#sh spanning-tree pvst-mode

PVST+ Enabled on:

Port      Method                  

1/1       Set by auto-detect      

1/2       Set by auto-detect      

1/3       Set by auto-detect  

 

!--- As PVST mode is not configured on these ports, IEEE STP BPDUs will be sending out of these ports, and on receiving PVST BPDU on these ports, PVST mode is automatically enabled.

-------------------

 

Verification of Spanning Tree Topology

 

VLAN 501

For VLAN 501, the VCS Fabric has a lower bridge priority than all the other switches so it is elected Root Bridge. The Eth 1/2 interface of MLXe-A router is in the Blocked state.

 

MLXPVST+TopologyforVLAN501.jpg 

   MLX PVST+ Topology for VLAN 501

 

 

-------------------

VCS1# show spanning-tree vlan 501 br

VLAN 501

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 501

                          Address 01e0.5200.01c2

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

                          Hello Time 2, Max Age 20, Forward Delay 15

 

      Bridge ID    Priority 501

                           Address 01e0.5200.01c2

                           Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface         Role   Sts    Cost       Prio  Link-type  Edge

 ---------------------------------------------------------------------------

 Te 100/4/36   DES   FWD  2000     128   P2P           No 

 Po 101           DES   FWD   2000    128   P2P           No 

 

 

telnet@MLXe-A#sh spanning-tree vlan 501

 

VLAN 501 - STP instance 0

--------------------------------------------------------------------

STP Bridge Parameters:

 

Bridge                           Bridge   Bridge   Bridge   Hold   LastTopology  Topology

Identifier                       MaxAge  Hello    FwdDly  Time   Change            Change

hex                                sec          sec      sec          sec     sec                    cnt

800000243899fb00   20            2          15            1         981                   14     

 

RootBridge                  RootPath  DesignatedBridge      Root  Max   Hel    Fwd

Identifier                       Cost          Identifier                        Port   Age    lo      Dly

hex                                 hex                                                             sec    sec   sec

01f501e0520001c2   2                01f501e0520001c2   1/1     20      2       15 

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

STP Port Parameters:

 

Port  Prio   Path   State                    Designat-   Designated                 Designated

Num   rity   Cost                                ed Cost      Root                              Bridge

1/1     128  2         FORWARDING   0                 01f501e0520001c2   01f501e0520001c2

1/2     128  2         BLOCKING          0                 01f501e0520001c2   01f501e0520001c2

1/3     128  2         FORWARDING   0                 01f501e0520001c2   01f501e0520001c2

6/4     128  4         FORWARDING   2                 01f501e0520001c2   800000243899fb00

 

!--- These path cost values shows MLX use “short mode” STP port cost by default in PVST+.

-------------------

 

VLAN 502

For VLAN 502, the MLXe-A router has a lower bridge priority than all the other switches so it is elected Root Bridge. The port-channel 101 interface of VCS Fabric is in the Blocked state.

 

MLXPVST+TopologyForVLAN502.jpg 

   MLX PVST+ Topology for VLAN 502

 

-------------------

VCS1# show spanning-tree vlan 502 br

VLAN 502

 

 Spanning-tree Mode: Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                   Address 0024.3899.fb02

                   Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the MLXe-A, the Root Bridge.

 

      Bridge ID    Priority 33270

                   Address 01e0.5200.01c2

                   Root Port Te 100/4/36

                   Hello Time 2, Max Age 20, Forward Delay 15

 

 Interface     Role         Sts     Cost       Prio  Link-type  Edge

 -----------------------------------------------------------------------------

 Te 100/4/36   RTPT  FWD  2000       128   P2P           No 

 Po 101            ALT     BLK   2000       128   P2P           No 

 

 

telnet@MLXe-A#sh spanning-tree vlan 502  

 

VLAN 502 - STP instance 2

--------------------------------------------------------------------

STP Bridge Parameters:

 

Bridge                           Bridge    Bridge   Bridge   Hold    LastTopology   Topology

Identifier                       MaxAge  Hello     FwdDly  Time   Change              Change

hex                                sec          sec        sec         sec     sec                       cnt

000000243899fb02  20             2           15            1         4037                    101    

 

RootBridge                RootPath  DesignatedBridge       Root    Max  Hel    Fwd

Identifier                     Cost           Identifier                        Port     Age  lo       Dly

hex                                                  hex                                              sec  sec   sec

000000243899fb02 0                000000243899fb02    Root    20     2       15 

 

!--- This is the MAC address of the MLXe-A, the Root Bridge.

 

STP Port Parameters:

 

Port    Prio  Path      State                     Designat-    Designated                 Designated

Num     rity  Cost                                   ed Cost        Root                              Bridge

1/1     128   2           FORWARDING    0                   000000243899fb02   000000243899fb02

1/2     128   2           FORWARDING    0                   000000243899fb02   000000243899fb02

1/3     128   2           FORWARDING    0                   000000243899fb02   000000243899fb02

6/4     128   4           FORWARDING    0                   000000243899fb02   000000243899fb02

------------------

 

Spanning Tree Convergence Time

Convergence time for a link or LAG failure is about 30 seconds, and convergence time for the recovery from a link failure or LAG failure is about 30 seconds.

 

Test Result Summary

The test result shows PVST+ in a Brocade VCS Fabric interoperates with a Brocade MLX router and that LAGs are treated as normal links in the PVST+.

 

MSTP Interoperability Test Result 

 

Configurations

The following is the configurations used in the MSTP interoperability test, with three MSTP instances, including default instance 0, enabled on the VCS Fabric and MLXe-A router.

  • The 'protocol spanning-tree mstp' command is configured on the VCS Fabric to enable MSTP
  •  Instance 1 for VLAN 1 and 501, instance 2 for VLAN 502, a region of VCS_Fabric, and a revision of 10 are configured for 'protocol spanning-tree mstp' mode.
  • The 'instance 1 priority 0' command on the VCS Fabric is configured in an effort to secure the Root Bridge position for MSTP instance 1,
  • The 'mstp instance 2 priority 0’ command is configured on MLXe-A router in an effort to secure the Root Bridge for MSTP instance 2:

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree mstp

 instance 1 vlan 1,501

 instance 1 priority 0

 

!--- This is configured in an effort to secure the Root Bridge position for MSTP instance 1.

 

 instance 2 vlan 502

 region VCS_Fabric

 revision 10

 

 

VCS1# show running-config interface Port-channel 101

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 no shutdown

!

VCS1# show running-config interface TenGigabitEthernet 100/4/36

interface TenGigabitEthernet 100/4/36

 fabric isl enable

 fabric trunk enable

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 no shutdown

 

 

telnet@MLXe-A#sh mstp config

mstp name VCS_Fabric                     

mstp revision 10

mstp instance 1  vlan 1

mstp instance 1  vlan 501

mstp instance 2  vlan 502

mstp instance 2 priority 0

mstp start

 

!--- This is configured in an effort to secure the Root Bridge for MSTP instance 2.

-------------------

 

Verification of Spanning Tree Topology

 

MSTP instance 1

For MSTP instance 1, the VCS Fabric has a lower bridge priority than all the other switches so it is elected the Root Bridge. The LAG interface of the MLXe-A router is in the Blocked state.

 

MLXMSTPInstance1Topology.jpg

   MLX MSTP Instance 1 Topology

 

-------------------

VCS1# show spanning-tree mst instance 1 br

 

 Instance: 1; Vlans: 1, 501

 MSTI Root         Address  01e0.5200.01c2   Priority  1

 MSTI Bridge     Address  01e0.5200.01c2   Priority  1

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

 

 Interface         Role   Sts     Cost        Prio  Link-type     Boundary  Edge

 ---------------------------------------------------------------------------------------------

 Te 100/4/36   DES   FWD  2000       128   P2P               No             No 

 Po 101            DES   FWD  2000       128   P2P               No             No 

 


telnet@MLXe-A#sh mstp 1    

MSTP Instance 1 - VLANs: 1 501

 

----------------------------------------------------------------------------

Bridge                          Max     RegionalRoot               IntPath    Designated                  Root   Root

Identifier                       Hop    Bridge                            Cost        Bridge                            Port   Hop

hex                                cnt       hex                                                  hex                                            cnt

800100243899fb00  20       000101e0520001c2   2000        000101e0520001c2   1/2    19 

 

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

Port    Pri    PortPath  P2P  Edge    Role                    State                    Designa-  Designated

Num           Cost         Mac   Port                                                                ted cost    bridge

1/1     128  2000         F       F           ALTERNATE     DISCARDING      0                000101e0520001c2

1/2     128  2000         F       F           ROOT                 FORWARDING   0                000101e0520001c2

1/3     128  2000         F       F           ALTERNATE     DISCARDING      0                000101e0520001c2

6/4     128  20000      F       T            DESIGNATED   FORWARDING   2000         800100243899fb00

 

!--- These path cost values shows MLX use “long mode” STP port cost by default in MSTP.

-------------------

 

 

MSTP instance 2

For MSTP instance 2, the MLXe-A router has a lower bridge priority than the other switches, so it is elected Root Bridge. The TenGig 100/4/36 interface of VCS Fabric is in the Blocked (Discarded) state.

 

MLXMSTPInstance2Topology.jpg 

   MLX MSTP Instance 2 Topology

 

-------------------

VCS1# show spanning-tree mst instance 2 br

 

 Instance: 2; Vlans: 502

 MSTI Root       Address  0024.3899.fb00   Priority  2

 

!--- This is the MAC address of MLXe-A, the Root Bridge.

 

 MSTI Bridge     Address  01e0.5200.01c2   Priority  32770

                 Root Port Po 101

 

 Interface     Role  Sts  Cost       Prio  Link-type        Boundary  Edge

 --------------------------------------------------------------------------

 Te 100/4/36   ALT   DSC  2000       128   P2P               No       No 

 Po 101        RTPT  FWD  2000       128   P2P               No       No 

 

!--- Te 100/4/36  of the VCS Fabric is in the Discarded state (that is, Blocked state).

 

 

telnet@MLXe-A#sh mstp 2

MSTP Instance 2 - VLANs: 502

 

----------------------------------------------------------------------------

Bridge                           Max   RegionalRoot            ntPath   Designated               Root   Root

Identifier                       Hop   Bridge                         Cost      Bridge                         Port    Hop

hex                                cnt     hex                                              hex                                          cnt

000200243899fb00  20      000200243899fb00  0            000200243899fb00 Root   20 

 

!--- This is the MAC address of MLXe-A, the Root Bridge.

 

Port    Pri    PortPath  P2P   Edge  Role                  State                    Designa-   Designated

Num           Cost          Mac   Port                                                            ted cost     bridge

1/1     128  2000         F         F        DESIGNATED  FORWARDING  0                 000200243899fb00

1/2     128  2000         F         F        DESIGNATED  FORWARDING   0                000200243899fb00

1/3     128  2000         F         F        DESIGNATED  FORWARDING   0                000200243899fb00

6/4     128  20000      F         T         DESIGNATED  FORWARDING   0                000200243899fb00

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or LAG failure is of around 210 msec, and convergence time for the recovery from a link failure or LAG failure is of around 210 msec.

 

Test Result Summary

The test result shows MSTP in a Brocade VCS interoperates with an MLX router and that LAGs are treated as normal links in the MSTP.

 

RPVST+ Interoperability Test Result

 

Configurations

The following is the configuration used in the RPVST+ interoperability test.

  • The 'protocol spanning-tree rpvst' command is configured on the VCS Fabric to enable PVST+
  • The 'rstp' command is configured for VLAN 501 and VLAN 502 on MLXe-A router to enable RPVST+
  • The 'vlan 501 priority 0' command is set on the VCS Fabric in an effort to secure the Root Bridge position for VLAN 501.
  • The 'rstp priority 0' command for VLAN 502 is set on the MLXe-A router in an effort to secure the Root Bridge position for VLAN 502 .
  • After the 'protocol spanning-tree pvst' command is configured on the VCS Fabric, the 'spanning-tree bpdu-mac 0100.0ccc.cccd' command must be configured on the VCS Fabric interfaces connected to the MLXe-A router.

 

-------------------

VCS1# show running-config protocol spanning-tree

protocol spanning-tree rpvst

 vlan 501 priority 0

 

!--- This is configured in an effort to secure the Root Bridge position for VLAN 501 and 503.



VCS1# show running-config interface Port-channel 101

interface Port-channel 101

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/36

interface TenGigabitEthernet 100/4/36

 fabric isl enable

 fabric trunk enable

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 spanning-tree bpdu-mac 0100.0ccc.cccd

 no spanning-tree shutdown

 no shutdown

 

telnet@MLXe-A#sh run

no spanning-tree

!

no dual-mode-default-vlan

!

!                                                                

vlan 1 name DEFAULT-VLAN                                         

 no untagged ethe 1/1 to 1/3 ethe 6/4                            

!                                                                

vlan 501                                                          

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

 rstp

 

!--- This enables RSTP for VLAN 501. On the MLX-A receiving PVST BPDU on these ports, PVST mode is automatically enabled as shown in the output of ‘sh spanning-tree pvst-mode’ below, and therefore, no additional command is required to interoperate with VCS’ PVST+ in the setup.                                                      

                                                     

vlan 502                                                          

 tagged ethe 1/1 to 1/3 ethe 6/4                                 

 rstp priority 0

 

!--- This is configured in an effort to enable RSTP for VLAN 502 and secure the Root Bridge position for VLAN 502.                                

 

telnet@MLXe-A#sh spanning-tree pvst-mode

PVST+ Enabled on:

Port      Method                  

1/1       Set by auto-detect      

1/2       Set by auto-detect      

1/3       Set by auto-detect      

 

!--- As PVST mode is not configured on these ports, IEEE STP BPDUs will be sending out of these ports, and on receiving Rapid PVST BPDU on these ports, PVST mode is automatically enabled.                   

-------------------

 

Verification of Spanning Tree Topology

 

VLAN 501

For VLAN 501, the VCS Fabric has a lower bridge priority than the other switches, so it is elected the Root Bridge. The LAG (eth 1/1 and eth 1/3) interface of MLXe-A router is in the Discarding (Blocked) state.

 

MLXRPVST+TopologyforVLAN501.jpg 

   MLX RPVST+ Topology for VLAN 501

 

-------------------

VCS1# show spanning-tree vlan 501 br

VLAN 501

 

 Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 501

                   Address 01e0.5200.01c2

                   Hello Time 2, Max Age 20, Forward Delay 15

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

      Bridge ID    Priority 501

                   Address 01e0.5200.01c2

                   Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                   Migrate Time 3 sec

 

 Interface          Role  Sts      Cost       Prio  Link-type        Edge

 --------------------------------------------------------------------------------

 Te 100/4/36   DES   FWD   2000       128   P2P               No 

 Po 101            DES   FWD   2000       128   P2P               No 

 

 

telnet@MLXe-A#sh rstp vlan 501       

 

VLAN 501 - RSTP instance 0

--------------------------------------------------------------------

RSTP (IEEE 802.1w) Bridge Parameters:

 

Bridge           Bridge Bridge Bridge Force    tx

Identifier       MaxAge Hello  FwdDly Version  Hold

hex              sec    sec    sec             cnt

800000243899fb20 20     2      15     Default  3   

 

RootBridge                 RootPath  DesignatedBridge    Root  Max   Hel   Fwd

Identifier                       Cost         Identifier                      Port   Age   lo      Dly

hex                                                  hex                                         sec    sec   sec

01f501e0520001c2  2000         01f501e0520001c2  1/2    20      2      15 

 

!--- This is the MAC address of the VCS Fabric, the Root Bridge.

 

RSTP (IEEE 802.1w) Port Parameters:

 

      <--- Config Params -->|<-------------- Current state ----------------->

Port  Pri     PortPath  P2P   Edge  Role                    State                     Designa-   Designated

Num          Cost         Mac   Port                                                                ted cost      bridge

1/1    128   2000        F        F         ALTERNATE      DISCARDING      0                  01f501e0520001c2 

1/2    128   2000        F        F         ROOT                  FORWARDING   0                   01f501e0520001c2 

1/3    128   2000        F        F         ALTERNATE      DISCARDING      0                  01f501e0520001c2 

6/4    128   20000      F        F         DESIGNATED  FORWARDING    2000           800000243899fb20 

 

!--- These path cost values shows MLX use “long mode” STP port cost by default in RPVST+.

-------------------

 

VLAN 502

For VLAN 502, the MLXe-A router has a lower bridge priority than the other switches so it is elected the Root Bridge. The TenGig 100/4/36 interface of MLXe-A router is in the Discarding (Blocked) state.

 

MLXRPVST+TopologyforVLAN502.jpg 

   MLX RPVST+ Topology for VLAN 502

 

-------------------

VCS1# show spanning-tree vlan 502  br

VLAN 502

 

 Spanning-tree Mode: Rapid Per-VLAN Spanning Tree Protocol

 

      Root ID      Priority 0

                          Address 0024.3899.fb21

                          Hello Time 2, Max Age 20, Forward Delay 15

!--- This is the MAC address of MLXe-A, the Root Bridge.

 

      Bridge ID    Priority 33270

                           Address 01e0.5200.01c2

                           Root Port Po 101

                           Hello Time 2, Max Age 20, Forward Delay 15, Tx-HoldCount 6

                        Migrate Time 3 sec

 

 Interface         Role     Sts    Cost       Prio    Link-type      Edge

 ----------------------------------------------------------------------------------

 Te 100/4/36   ALT      DSC  2000       128   P2P               No 

 Po 101            RTPT  FWD  2000       128   P2P               No 

 

!--- TenGig 100/4/36 of the VCS Fabric is in the Discarded (Blocked) state.

 

telnet@MLXe-A#sh rstp vlan 502

 

VLAN 502 - RSTP instance 1

--------------------------------------------------------------------

RSTP (IEEE 802.1w) Bridge Parameters:

 

Bridge           Bridge Bridge Bridge Force    tx

Identifier       MaxAge Hello  FwdDly Version  Hold

hex              sec    sec    sec             cnt

000000243899fb21 20     2      15     Default  3   

 

RootBridge                  RootPath   DesignatedBridge     Root  Max   Hel     Fwd

Identifier                       Cost           Identifier                       Port    Age   lo       Dly

hex                                                    hex                                            sec   sec    sec

000000243899fb21   0                 000000243899fb21  Root   20      2       15 

 

!--- This is the MAC address of MLXe-A, the Root Bridge.

 

 

RSTP (IEEE 802.1w) Port Parameters:

 

      <--- Config Params -->|<-------------- Current state ----------------->

Port  Pri      PortPath  P2P   Edge   Role                   State                     Designa-    Designated

Num           Cost          Mac   Port                                                               ted cost      bridge

1/1     128   2000         F       F          DESIGNATED   FORWARDING   0                  000000243899fb21 

1/2     128   2000         F       F          DESIGNATED   FORWARDING   0                  000000243899fb21 

1/3     128   2000         F       F          DESIGNATED   FORWARDING   0                  000000243899fb21 

6/4     128   20000       F      F           DESIGNATED   FORWARDING   0                  000000243899fb21 

 

-------------------

 

Spanning Tree Convergence Time

Convergence time for a link or LAG failure in the VCS Fabric is about 240 msec, and convergence time for the recovery from a link failure or LAG failure is about 90 msec.

 

Test Result Summary

The test result shows RPVST+ in the Brocade VCS Fabric interoperates with the MLX router, and that LAGs are treated as normal links in the RPVST+.

 

Connecting A VCS Fabric to an Existing STP Network

This section has test results from a VCS Fabric with NOS 4.0.x being connected to existing Cisco switches’ STP network. It validates that NOS 4.0.x with STP can be integrated seamlessly to an existing Cisco switches’ STP network.

 

Test Topology Diagram

 

The figure below shows the test network topology diagram.

 

STPInteroperabilityTestBedNetwork.jpg    Test Bed Network

 

 

Test Methodology

The Cisco switches’ simulate an existing network running STP. It consists of two Cisco Catalyst 6500 switches, and two Cisco Catalyst 3750 switches. The Cisco Catalyst 6500 switches are running IOS 122-33.SXI, and the Cisco Catalyst 3750 switches are running either IOS 15.0(1)SE or 12.2(46)SE.

 

The VCS Fabric VCS1 has NOS 4.0.x and is connected to existing Cisco network running STP. It consists of six VDX Switches (two VDX8770s, two VDX 6730s, and two VDX 6720s), and is running NOS 4.0.0. To form the VCS Fabric, VDX 6720-A, VDX 6720-B, VDX 6730-A and VDX 6730-B are connected to the VDX8770-A and VDX8770-B switches via TenGigabitEthernet’s links in a Brocade ISL Trunk. VCS1 is connected to the existing Cisco network via two 2x10GE LACP-based VCS Fabric vLAGs (port-channel 1 and port-channel 2) to ensure high availability for node and link failures. The VCS vLAGs are enabled as Layer 2 trunks using 802.1Q (dot1q) and allow all VLANs.

 

All interconnections between the Cisco switches are 10GEs or 1GEs, and the ports are enabled for Layer 2 trunks using 802.1Q (dot1q) allowing all VLANs.

 

To simulate host and server traffic, flows are established using the Spirent Test Center (STC) tool. 300 Mbps traffic flows are sent on each STC port and distributed using full mesh with a packet size of 128 bytes.

 

Configuration

The following are Rapid PVST+ configuration commands for the Catalyst 6500 Switches. The bridge priority is set to 0 for VLAN 501 on Cat6500-A in an effort to secure the root bridge position.

 

--------------------

Cat6500-A#sh running-config | in spanning-tree

spanning-tree mode rapid-pvst

spanning-tree vlan 501 priority 0

 

Cat6500-B#sh running-config | in spanning-tree

spanning-tree mode rapid-pvst

--------------------

 

The following is the VCS Fabric vLAG configuration for VCS1. For more detaila about how design VCS Fabric vLAG and how to verify vLAG state on Brocade VDX Switches, see the following reference.

 

References

 

------------------

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no shutdown

 

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/34

interface TenGigabitEthernet 100/4/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 101/2/34

interface TenGigabitEthernet 101/2/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 1 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 100/4/33

interface TenGigabitEthernet 100/4/33

 no fabric isl enable

 no fabric trunk enable

 channel-group 2 mode active type standard

 lacp timeout long

 no shutdown

 

VCS1# show running-config interface TenGigabitEthernet 101/2/33

interface TenGigabitEthernet 101/2/34

 no fabric isl enable

 no fabric trunk enable

 channel-group 2 mode active type standard

 lacp timeout long

 no shutdown

-----------------------

 

Test Result

 

Rapid PVST+ Topology of Existing Cisco STP network

Below is a Spanning Tree topology of Rapid PVST+ for VLAN 501 prior to the VCS Fabric being connected. The Cat6500-A switch is the Root Bridge. 

 

ExistingRPVST+TopologyforVLAN501.jpg

   Existing RPVST+ Topology for VLAN 501

 

In this setup, Rapid PVST+ uses ‘short mode’ STP port cost by default. Therefore, for 10Gbps’ bandwidth, the STP port cost is 2 and for 1Gbps’ bandwidth, the STP port cost is 1 as shown in the table below.

 

STP Port Cost Value

Bandwidth

Short Mode STP

port cost value

Long Mode STP

port cost  value

10 Mbps

100

2,000,000

100 Mbps

19

200,000

1 Gbps

4

20,000

N X 1 Gbps

3

10,000

10 Gbps

2

2,000

100 Gbps

N/A

200

1 Tbps

N/A

20

10 Tbps

N/A

2

 

STP port cost values from the ‘show spanning-tree’ command should be used to determine if Cisco Catalyst Switches use short mode or long mode port cost. 

 

Spanning Tree Protocol calculates the path cost to the root bridge, and it selects the root port based on the path cost to the root bridge. The port on the path with the lowest path cost to the root bridge becomes the root port. The root port is always in the Forwarding state.

 

Therefore, in the existing Cisco network, the Gig 1/0/15 interface of the Cat3750-D switch is in the ‘Blocking’ state since these ports are on segments where more than one designated port exists and their path cost to the root bridge is higher.

 

Rapid PVST+ Topology after VCS being integrated to the Existing Cisco STP Network

The VCS Fabric uses ‘long mode’ STP port costs by default for all Spanning Tree Protocols. For

Rapid PVST+, set the port cost to 2,000 for the port-channel interfaces in the VCS Fabric. This higher cost makes the port-channel interface in the VCS Fabric the least preferred segment. Those ports, such as port-channel 2, will be in the ‘Blocking’ state as shown below. This means there is no STP topology change in the existing Cisco network when the VCS Fabric is connected. and no traffic disruption to flows in the existing Cisco network.

 

With the default STP port cost, a VCS Fabric seamlessly connects to an existing Cisco network running Rapid PVST+.

 

ExistingRPVST+TopologyConnectedtoVCSFabric.jpg

   Existing RPVST+ Topology Connected to VCS Fabric

 

 

When the Existing Cisco network runs PVST+

PVST+ of existing Cisco STP network uses ‘short mode’ STP port cost by default like Rapid PVST+, so using default STP port cost, the VCS Fabric was seamlessly integrated to the existing Cisco network running Rapid PVST+ with no traffic disruption in the existing Cisco STP network.

 

When the Existing Cisco network runs PVST+

PVST+ of existing Cisco STP network uses ‘short mode’ STP port cost by default like Rapid PVST+, so using default STP port cost, the VCS Fabric was seamlessly integrated to the existing Cisco network running Rapid PVST+ with no traffic disruption in the existing Cisco STP network.

 

When the Existing Cisco network runs MSTP

 

MSTP Topology of Existing Cisco STP network

Below is a Cisco network with a Spanning Tree topology and MSTP instance 1 prior to the VCS Fabric being connected. The Cat6500-A switch is the root bridge. 

 

ExistingMSTPTopology.jpg

   Existing MSTP Topology

 

MSTP in an existing Cisco network uses ‘long mode’ STP port cost by default. Therefore, for 10Gbps’ bandwidth, its STP port cost is 2,000 and for 1Gbps bandwidth, its STP port cost is 20,000 as shown in the MSTP table below.

 

STP Port Cost Value

Bandwidth

Short Mode STP

port cost value

Long Mode STP

port cost  value

10 Mbps

100

2,000,000

100 Mbps

19

200,000

1 Gbps

4

20,000

N X 1 Gbps

3

10,000

10 Gbps

2

2,000

100 Gbps

N/A

200

1 Tbps

N/A

20

10 Tbps

N/A

2

 

STP port cost values from the ‘show spanning-tree’ command should be used to determine if Cisco Catalyst switches use the short or long mode port cost metric.

 

Spanning Tree Protocol calculates the path cost to the root bridge, and it selects the root port based on the path cost to the root bridge. The port with the lowest path cost to the root bridge becomes the root port. The root port is always in the ‘Forwarding’ state.

 

Therefore, in the Rapid PVST+ topology of the existing Cisco network, the Gig 1/0/15 interface of the Cat3750-D switch is in the ‘Blocking’ state since these ports are on segments where more than one designated port exists and their path cost to the root bridge is the.

 

MSTP Topology after VCS being integrated to the Existing Cisco STP Network

The VCS Fabric uses ‘long mode’ STP port cost by default for all the Spanning Tree Protocols, so 

MSTP sets STP port cost to 2,000 for the port-channel interfaces of the VCS Fabric since they are 10 GbE interfaces.

 

When the VCS Fabric is integrated to the existing Cisco network, some ports in the existing Cisco network could change from ‘Forwarding’ to ‘Blocking’ state. This can cause traffic disruption in the existing Cisco environment.

 

To avoid larger value’s STP port cost should be used for the port-channel interfaces in the VCS fabric. The makes sure the port-channel interfaces least preferred so they are in the ‘Blocking’ state. 

 

An STP port cost value of 200,000 is used on the port-channel interfaces of the VCS Fabric. The port-channel 2 interface in the VCS Fabric is in the ‘Blocking’ so there is no traffic disruption in the existing Cisco network. 

 

---------------------

VCS1# show running-config interface Port-channel 1

interface Port-channel 1

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 spanning-tree instance 1 cost 200000

 no shutdown

 

VCS1# show running-config interface Port-channel 2

interface Port-channel 2

 vlag ignore-split

 switchport

 switchport mode trunk

 switchport trunk allowed vlan all

 switchport trunk tag native-vlan

 no spanning-tree shutdown

 spanning-tree instance 1 cost 200000

 no shutdown

--------------------

 

MSTPTopologyConnectedtoVCSFabric.jpg 

   MSTP Topology Connected to VCS Fabric

 

 

Brocade ISL Trunk Failure Impact on Cisco Network

This section shows how a VCS Fabric Brocade ISL Trunk failure with NOS 4.0.x impacts an existing Cisco STP switch network. 

 

Test Topology Diagram

The figure below shows the test network topology.

 

ISLFailureTestNetworkTopology.jpg

   ISL Failure Test Network Topology

 

Test Methodology

The Cisco network is running STP and consists of two Cisco Catalyst 6500 Switches, and two Cisco Catalyst 3750 Switches. The Cisco Catalyst 6500 Switches are running IOS 122-33.SXI, and the Cisco Catalyst 3750 Switches are running either IOS 15.0(1)SE or 12.2(46)SE.

 

The VCS Fabric, VCS1, is running NOS 4.0.1 and is configured with STP. It consists of three VDX Switches (two VDX8770s, and one VDX 6720). To form the VCS Fabric, one VDX 6720, and two VDX6770 are connected via TenGigabitEthernet links in a Brocade ISL Trunk. VCS1 is connected to Cisco switches via two 2x10GE LACP-based VCS Fabric vLAGs (port-channel 1 and port-channel 2) to ensure high availability for node and link failures. All vLAGs are enabled as Layer 2 trunks using 802.1Q (dot1q) and allow all VLANs.

 

All interconnections between Cisco switches are 10GEs or 1GEs, and all the ports are enabled as Layer 2 trunks using 802.1Q (dot1q) and allow all VLANs.

 

To simulate host and server traffic, flows are established using the Spirent Test Center (STC) tool. 300 Mbps traffic flows are sent on each STC port and distributed using full mesh, with a packet size of 128 bytes.

 

Testing ISL Trunk Failure

This tests the impact of a single Brocade VCS Fabric ISL Trunk failure when redundant ISL Trunks are configured between the VCS Fabric and an existing Cisco network. The VCS Fabric is configured with Rapid PVST+.

 

Test Result

The VCS Fabric has redundant Brocade ISL trunks as shown above. When a Brocade ISL Trunk (the Tengig 11/0/5 interface on VCS1) is brought down, the Spanning Tree topology does not change.

 

The traffic convergence time within the VCS Fabric was about 100 msec when the Brocade ISL trunk was brought down. In a VCS Fabric, the STP BPDU frames are sent every 2 seconds. VCS Fabric convergence happens before STP in the Fabric detects a topology change so no STP BPDU for a topology change are sent and the Cisco network is not affected by the removal of a Brocade ISL Trunk.

 

Conclusion

Brocade NOS 4.0.x VCS Fabric supports the following flavors of Spanning Tree, and they interoperate with Cisco Switches and Brocade MLX. It allows Brocade NOS 4.0.x VCS Fabric to be seamlessly integrated into the existing STP infrastructure.

 

  • IEEE 802.1D STP
  • IEEE 802.1w RSTP
  • IEEE 802.1s MSTP
  • PVST+
  • RPVST+